Systems and methods for prioritization of data for intelligent discard in a communication network

ABSTRACT

Systems and methods for optimizing system performance of capacity and spectrum constrained, multiple-access communication systems by selectively discarding packets are provided. The systems and methods provided herein can drive changes in the communication system using control responses. One such control responses includes the optimal discard (also referred to herein as “intelligent discard”) of network packets under capacity constrained conditions. The systems and methods prioritize packets and make discard decisions based upon the prioritization. Some embodiments provide an interactive response by selectively discarding packets to enhance perceived and actual system throughput, other embodiments provide a reactive response by selectively discarding data packets based on their relative impact to service quality to mitigate oversubscription, others provide a proactive response by discarding packets based on predicted oversubscription, and others provide a combination thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 14/797,505filed on Jul. 13, 2015, which is a continuation of application Ser. No.13/953,422 (now U.S. Pat. No. 9,112,802) filed on Jul. 29, 2013, whichis a continuation of application Ser. No. 13/182,703 (now U.S. Pat. No.8,531,961) filed on Jul. 14, 2011, which claims the benefit of U.S.provisional patent application Ser. No. 61/421,510 filed on Dec. 9,2010, all of which are hereby incorporated by reference. applicationSer. No. 13/182,703 is a continuation in part of U.S. patent applicationSer. No. 13/155,102 (now U.S. Pat. No. 8,627,396) filed Jun. 7, 2011,which is hereby incorporated by reference. application Ser. No.13/182,703 is also a continuation in part of U.S. patent applicationSer. No. 12/813,856 (now U.S. Pat. No. 8,068,440) filed on Jun. 11, 2010which claims the benefit of U.S. provisional patent application Ser. No.61/186,707 filed on Jun. 12, 2009, U.S. provisional patent applicationSer. No. 61/187,113 filed on Jun. 15, 2009, and U.S. provisional patentapplication Ser. No. 61/187,118 filed on Jun. 15, 2009, all of which arehereby incorporated by reference.

FIELD OF THE INVENTION

The present invention generally relates to the field of communicationsystems and more specifically to systems and methods for optimizingsystem performance by selectively discarding packets in capacity andspectrum constrained, multiple-access communication systems.

BACKGROUND

In capacity and spectrum constrained, multiple-access communicationsystem, two goals are omnipresent: the successful transfer ofinformation, and the minimization of such transmissions from disruptingother transfers. Often these goals are in conflict with each other, andthus represent opportunity for system optimization.

In a cellular network, for example, the creation of a positive userexperience is the success criteria for the transport of information.Often this metric is further defined as the quality of service of aparticular user task or application. In contrast, this activity can beviewed by its effect on other network users, specifically through theusage of limited system resources and through the creation of channelinterference.

SUMMARY

Systems and methods for optimizing system performance of capacity andspectrum constrained, multiple-access communication systems byselectively discarding packets are provided. The systems and methodsprovided herein can drive changes in the communication system usingcontrol responses. One such control response includes the optimaldiscard (also referred to herein as “intelligent discard”) of networkpackets under capacity constrained conditions.

In one aspect a system managing video transmission responsive to networkconditions includes a determination module configured to determine apriority value for each frame in a video stream, each frame having aframe type, wherein the priority value of each frame is based on atleast in part on the frame type; and a selection module configured todiscard one or more frames based at least in part on the priority valueof the frames.

In a further aspect each frame comprises one or more slices having aslice type and the determination module is configured to determine apriority value for the one or more slices based at least in part on theslice type. Additionally, the selection module is configured to discardone or more slices based on the priority values of the slices. Thediscarded slices can be redundant slices. Further, the determination ofthe priority value of switching slices can be dynamic. In a furtheraspect each slice comprises a plurality of data partitions, each datapartition having a type, and the determination module is configured todetermine a priority value for each data partition and the priorityvalue of each data partition is based at least in part based on theframe type.

In a further aspect the determination module is configured to determinethe priority value for each frame based at least in part on the priorityvalues for the slices in the frame.

In another aspect each slice comprises one or more macroblocks having amacroblock type, and the priority of each slice is determined based atleast in part on the macroblock types of the macroblocks in the slice.Alternatively, the priority value for each slice is based at least inpart on the size of the slice. Additionally, the priority value for eachframe can be based at least in part on the size of the frame. Further,the priority value for each frame can be based at least in part onwhether an adjacent frame has been discarded.

In a further aspect each frame comprises one or more macroblocks havinga macroblock type, and the priority of each slice is determined based atleast in part on the macroblock types of the macroblocks in the slice.

A further aspect relates to a system for managing video transmissionresponsive to network conditions having a determination moduleconfigured to determine a priority value for each frame in a group ofpictures (GOP), wherein one or more of the frames depends on anotherframe for decoding, and wherein the priority value of each frame isbased at least in part on the number of frames which depend from theframe.

In a further aspect a computer implemented method for managing videotransmission responsive to network conditions includes receiving aplurality of frames in a group of pictures (GOP) to be transmitted toone or more devices; determining that insufficient bandwidth isavailable for sending each frame in the GOP; determining a priorityvalue for each frame in the GOP, wherein one or more of the framesdepends on another frame for decoding, and wherein the priority value ofeach frame is based at least in part on the number of frames whichdepend from the frame; discarding one ore more of the frames based onthe priority value of each frame; and transmitting the non-discardedframes to the one or more devices.

In another aspect a computer implemented method for managing videotransmission responsive to network conditions includes receiving aplurality of frames in a video stream to be transmitted to one or moredevices; determining that insufficient bandwidth is available forsending each frame in the video stream; determining a priority value foreach frame in the video frame, each frame having a frame type, whereinthe priority value of each frame is based on at least in part on theframe type; discarding one or more of the frames based on the priorityvalue of each frame; and transmitting the non-discarded frames to theone or more devices.

Other features and advantages of the present invention should beapparent from the following description which illustrates, by way ofexample, aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the present invention, both as to its structure andoperation, may be gleaned in part by study of the accompanying drawings,in which like reference numerals refer to like parts, and in which:

FIG. 1 is a block diagram of a wireless communication network in whichthe systems and methods disclosed herein can be implemented according toan embodiment;

FIG. 2A is block diagram of another wireless communication network inwhich the systems and methods disclosed herein can be implementedaccording to an embodiment;

FIG. 2B is a block diagram of an access point or base station that canbe used to implement the systems and methods illustrated in FIGS. 3-6according to an embodiment;

FIG. 3 is a logical block diagram of a system for mitigating effects ofinterference scenarios in a wireless communication network according toan embodiment;

FIG. 4 is a flow diagram of a method that can be used to generate thefeedforward and feedback adjustments of the radio frequency (RF) networkand system environment using the system illustrated in FIG. 3 accordingto an embodiment;

FIG. 5 is a flow diagram of a method for mitigating effects ofinterference scenarios in a wireless communication network according toan embodiment;

FIG. 6 is a flow diagram of a method for mitigating effects ofinterference scenarios in a wireless communication network according toan embodiment;

FIG. 7 is a logical block diagram of a system for mitigating effects ofinterference scenarios in a wireless communication network according toan embodiment;

FIG. 8A is a diagram of plurality of frames in a group of picturesaccording to an embodiment;

FIG. 8B is a diagram of plurality of frames in a group of picturesaccording to an embodiment;

FIG. 9 is a flow diagram of a method for determining priority for framesin a group of pictures according to a embodiment;

FIG. 10 is a diagram of plurality of frames in a group of picturesaccording to an embodiment;

FIG. 11 is a diagram of plurality of frames in a group of picturesaccording to an embodiment;

FIG. 12 is a diagram of plurality of frames in a group of picturesaccording to an embodiment;

FIG. 13 is a diagram of plurality of frames in a group of picturesaccording to an embodiment;

FIG. 14 is a diagram of plurality of frames in a group of picturesaccording to an embodiment;

FIG. 15 is a flow diagram of a method for determining burdens for framesin a group of pictures according to a embodiment;

FIG. 16 is a diagram of a weighting factor vector according to anembodiment;

FIG. 17 is a diagram of a weighting factor vector according to anembodiment;

FIG. 18 is a diagram of a frame burden table and frame priority vectoraccording to an embodiment;

FIG. 19 is a flow diagram of a method for determining burdens for framesin a group of pictures according to a embodiment;

FIG. 20 is a diagram of a frame burden table and frame priority vectoraccording to an embodiment;

FIG. 21 is a diagram of a weighting factor table according to anembodiment;

FIG. 22 is a flow diagram of a method for determining priority of aframe according to an embodiment; and

FIG. 23 is a flow diagram of a method for determining priority of aframe according to an embodiment.

FIG. 24 is a functional block diagram of an embodiment of a system thatuses the prioritization to determine which data packets to discard andwhich to transmit to the end recipient.

FIG. 25 is a flow diagram of a method of discarding packets as they arebeing queued by the scheduler.

FIG. 26 is a flow diagram of a method of discarding packets after theyare placed in the buffers used by the scheduler.

FIG. 27 is a flow diagram of a method for determining the GOP structureand average size.

FIG. 28 is a graphical representation of an example of relative framesizes for an N=12, M=3 GOP.

FIG. 29 is a graphical representation of the example of relative framesizes for an N=12, M=3 GOP from FIG. 28 with selected frames discarded.

FIG. 30 is a graphical representation of the example of relative framesizes for an N=12, M=3 GOP from FIG. 28 with further selected framesdiscarded.

FIG. 31 is a graphical representation of the example of relative framesizes for an N=12, M=3 GOP from FIG. 28 with still further selectedframes discarded.

FIG. 32 is a flow diagram of a method for call admission.

FIG. 33 is a flow diagram of a method that allows graceful degradationof services in resource reduction situations.

DETAILED DESCRIPTION

Some embodiments provide systems and methods for a multivariate controlsystem that can be implemented in a base station or other device. Thecontrol system can be configured to for mitigating the effects ofvarious interference scenarios in a capacity and spectrum constrained,multiple-access communication network. In other embodiments, the controlsystem can be configured for making adjustments to or changing theoverall bandwidth demands. The systems and methods provided herein candrive changes in the communication system using control responses. Onesuch control responses includes the optimal discard (also referred toherein as “intelligent discard”) of network packets under capacityconstrained conditions. Some embodiments provide an interactive responseby selectively discarding packets to enhance perceived and actual systemthroughput, other embodiments provide a reactive response by selectivelydiscarding data packets based on their relative impact to servicequality to mitigate oversubscription, others provide a proactiveresponse by discarding packets based on predicted oversubscription, andothers provide a combination thereof.

According to an embodiment, an interactive response technique isprovided that allows transmission and radio access network (RAN)/radiofrequency (RF) parameters to be optimized for robustness againstinterference from neighboring cells and optimized for mitigation ofinterference to neighboring cells. These optimizations are performed bydetermining and considering throughput levels and associated qualityscores for a set of active services. A high quality user experience canbe maintained where perceived and actual system throughput is controlledby selectively discarding packets.

According to an embodiment, a reactive response technique is providedthat allows selected data packets to be discarded based on theirrelative impact to service quality in order to mitigate oversubscriptioncaused by modification of transmission parameters or by varying theRAN/RF parameters to mitigate interference between neighboring cells.Reactively discarding packets in reaction to varying available bandwidthcan provide an increase in perceived quality of the user experience fora given amount of bandwidth and can provide an increase in the number ofservices that can be maintained for a given amount of bandwidth.

According to an embodiment, a proactive response technique is providedthat can improve the quality of the user experience and systemthroughput by predicting oversubscription and selectively discardingpackets or marking packets for efficient discard prior to anticipatedoversubscription. Proactively discarding packets in reaction toanticipated oversubscription can provide an increase in perceivedquality of the user experience for a given amount of bandwidth and canprovide an increase in the number of services that can be maintained fora given amount of bandwidth and for a given amount of change inbandwidth. In an embodiment, selectively proactively discarding packetscan be used to optimize transmission and RAN/RF parameters to increaserobustness against interference from neighboring cells and to mitigateinterference to neighboring cells in anticipation of events which causea need for such parameter changes. Proactively applying intelligentdiscard and considering intelligent discard to proactively modifytransmission and RAN/RF parameters before a bandwidth limiting eventoccurs can provide a better user experience transition than can beachieved by waiting to apply intelligent discard and to modifytransmission and RAN/RF parameters until after such a bandwidth limitingevent.

Some embodiments provide systems and methods for a multivariate controlsystem that can be implemented in a base station. The control system canbe configured to mitigate the effects of various interference scenariosin a capacity and spectrum constrained, multiple-access communicationnetwork. In other embodiments, the control system can be configured formaking adjustments to or changing the overall bandwidth demands.

The systems and methods disclosed herein can be applied to variouscapacity-limited communication systems, including but not limited towire line and wireless technologies. For example, the systems andmethods disclosed herein can be used with Cellular 2G, 3G, 4G (includingLong Term Evolution (“LTE”), LTE Advanced, WiMax), WiFi, Ultra MobileBroadband (“UMB”), cable modem, and other wire line or wirelesstechnologies. Although the phrases and terms used herein to describespecific embodiments can be applied to a particular technology orstandard, the systems and methods described herein are not limited tothe these specific standards.

Although the phrases and terms used to describe specific embodiments mayapply to a particular technology or standard, the methods describedremain applicable across all technologies.

According to an embodiment, the systems and methods disclosed herein,including intelligent discard of packets, can be practiced within anyentity within the communications system that performs scheduling. Thisincludes the scheduling of downlink bandwidth by any form of basestation, including macro cell, Pico cell, enterprise Femtocell,residential Femtocell, relays, or any other form of base station.According to an embodiment, intelligent discard can be performed by anyform of device which transmits in the uplink direction including userdevices, both fixed and mobile, and relay devices. According to anembodiment, intelligent discard can be performed by a schedulingalgorithm or module, housed in the core network which centrally directsthe actions of devices. According to an embodiment, intelligent discardcan be predicatively performed by an entity such as a base station thatallocates uplink bandwidth for use by another entity, such as a userdevice known to be capable of intelligent discard. The base station andthe user device can negotiate whether or not the user device hasintelligent discard capability, or in some embodiments, whether the userdevice has intelligent discard capability can be determined based on themodel identification of the user device.

Basic Deployments

FIG. 1 is a block diagram of a wireless communication network in whichthe systems and methods disclosed herein can be implemented according toan embodiment. FIG. 1 illustrates a typical basic deployment of acommunication system that includes macro cells, Pico cells, andenterprise Femtocells. In a typical deployment, the macro cells cantransmit and receive on one or many frequency channels that are separatefrom the one or many frequency channels used by the small form factor(SFF) base stations (including Pico cells and enterprise or residentialFemtocells). In other embodiments, the macro cells and the SFF basestations can share the same frequency channels. Various combinations ofgeography and channel availability can create a variety of interferencescenarios that can impact the throughput of the communications system.

FIG. 1 illustrates a typical Pico cell and enterprise Femtocelldeployment in a communications network 100. Macro base station 110 isconnected to a core network 102 through a standard backhaul 170.Subscriber stations 150(1) and 150(4) can connect to the network throughmacro base station 110. In the network configuration illustrated in FIG.1, office building 120(1) causes a coverage shadow 104. Pico station130, which can be connected to core network 102 via standard backhaul170, can provide coverage to subscriber stations 150(2) and 150(5) incoverage shadow 104.

In office building 120(2), enterprise Femtocell 140 provides in-buildingcoverage to subscriber stations 150(3) and 150(6). Enterprise Femtocell140 can connect to core network 102 via ISP network 101 by utilizingbroadband connection 160 provided by enterprise gateway 103.

FIG. 2A is a block diagram of another wireless communication network inwhich the system and methods disclosed herein can be implementedaccording to an embodiment. FIG. 2A illustrates a typical basicdeployment in a communications network 200 that includes macro cells andresidential Femtocells deployed in a residential environment. Macro cellbase station 110 can be connected to core network 102 through standardbackhaul 170. Subscriber stations 150(1) and 150(4) can connect to thenetwork through macro base station 110. Inside residences 220,residential Femtocell 240 can provide in-home coverage to subscriberstations 150(7) and 150(8). Residential Femtocells 240 can connect tocore network 102 via ISP network 101 by utilizing broadband connection260 provided by cable modem or DSL modem 203.

FIG. 2B is a high level functional block diagram of an access point orbase station. It should be noted that the same or similar functionalblocks are also present in other elements of a wireless communicationsystem (e.g., macro cells, Pico cells, enterprise Femtocells andsubscriber stations) and reference herein to the system depicted in FIG.2B are intended to also apply to such other elements. The base stationincludes a modem section 272 which transmits and receives wirelesssignals. The modem 272 is also sometimes referred to as an RF card. Themodem can also measure and determine various characteristics of thereceived signals. The control and management section 270 is generallyresponsible for the operation of the base station. The control andmanagement section 270 includes a higher level control section 274 andone or more MAC (medium access control) layers or modules 276 and PHY(physical) layers or modules 280. In general, the MAC layer 276 managesand maintains communications between stations (subscriber stationsaccess points/base station) by coordinating access to a shared radiochannel and utilizing protocols that enhance communications over awireless medium. Within the MAC layer 276 is a scheduler 278. Ingeneral, the PHY layer 280 is responsible for the transmission of bitsover the wireless link. In some embodiments described herein, thecontrol and management section 270 implements the system and methoddescribed herein.

Interference Scenarios

Various interference scenarios can result in decreases in perceived andactual performance of the communications network. For example, the 3rdGeneration Partnership Project (3GPP) has identified a number ofinterference scenarios in a technical report (3GPP TR 25.967), which ishereby incorporated by reference in its entirety. Some examples ofinterference scenarios include: (1) Uplink (UL) transmission fromsubscriber station to SFF base station interfering with UL of macro cellbase station; (2) Downlink (DL) transmission of SFF base stationinterfering with macro cell base station DL; (3) UL transmission fromsubscriber station to macro cell base station interfering with SFF basestation uplink; (4) DL transmission of macro base station interferingwith SFF base station DL; (5) UL transmission from subscriber station toSFF base station interfering with UL of SFF station; (6) DL transmissionof SFF base station interfering with SFF base station DL; and (7)interference to and from systems of other technologies.

Avoidance and Mitigation Techniques

FIG. 3 is a logical block diagram illustrating an example of thefunctional elements of a multivariate control system for mitigating theeffects of various interference scenarios in a capacity and spectrumconstrained, multiple-access communication network, such as thosedescribed above, according to an embodiment. The functionality of thesystem is show in FIG. 3 broken down into modules to more clearlyillustrate the functionality of the control system. The control systemcan be implemented in a macro cell base station, Pico cell, orFemtocell, such as macro cell base station 110, pico station 130, andresidential Femtocell 240 illustrated in FIGS. 1, 2A, and 2B.Alternatively, portions can be distributed to a base station controller(BSC) or other element of core network 102. In one embodiment, thecontrol system is implemented in the MAC layer 276 of the base stationshown in FIG. 2B.

In an embodiment, the control system can be configured to provideoptimal responses in the following areas: (1) interference avoidance and(2) interference mitigation. The control system can avoid radiofrequency (RF) interface through optimal control of RF/RAN parameters.The control system can also preserve packet quality of service (“QoS”)when interference cannot be avoided or when interference avoidance ormitigation result in decreased bandwidth availability.

According to an embodiment, various types of input parameters can beused by the control system. In an embodiment, these input parameters canbe divided into policy parameters and environment parameters. Policyparameters module 310 can be configured to receive policy parameters,and environment parameter module 320 can be configured to receiveenvironment parameters. The policy parameters received by policyparameters module 310 are operational requirements defined by, forexample, the network provider. These policy parameters can be brokendown into two groups of system requirements: QoS policies andinterference policies. In an embodiment, the policy parameters caninclude QoS policies at an application level, by time/day, by servicelevel agreement (SLA), manually define QoS parameters, or a combinationthereof. The policy parameters can also include policies related tovarious interference related parameters, such as received signalstrength indicator (RSSI), energy per bit to noise power spectraldensity ratio (E_(b)/N₀), carrier-to-interference ratio (C/I), noisefloor (the measure of the signal created from the sum of all of thenoise source and unwanted signals), or other interference relatedparameters. The control system can use the policy parameters todetermine the types of actions that can be undertaken to avoidinterference and to mitigate interference when interference cannot beavoided.

The environment input parameters received by environment parametermodule 320 comprise real-time information that describes the operatingstatus of the RF network and system environment. This information can beobtained at a base station (e.g., a macro cell, Pico cell, or Femtocellas depicted in FIGS. 1, 2A, and 2B) or reported by a subscriber stationand can also include information about neighboring cells. Theenvironment input parameters 320 can be further divided into twocategories of input parameters: self environment parameters and remoteenvironment parameters. The self environment parameters are environmentparameters related to or obtained by the station in which the controlsystem is implemented. For example, in one embodiment, the selfenvironment parameters can include Layer 1-7 parameters of both the RFand backhaul Femtocell or Pico cell ports. Remote environment parametersare related to or obtained from other cells and/or user equipmentoperating nearby the base station that can have an impact on theoperating environment of the base station. For example, in anembodiment, the remote environment parameters can include Layer 1-7parameters of the user equipment (UE), Core Network and otherneighboring cells defined by base stations, such as evolved Node B (eNBor eNodeB), and pico stations and Femtocells, such as evolved Home NodeB devices (eHNB or Home eNodeB), collectively e(H)NB devices.

From the policy parameters and environment parameters, additional setsof parameters can be derived including control set points, real-timeprofile, and patterns. Control set points module 315 is configured toderive control set points from the policy inputs received by the policyparameters module 310 from the network provider or can be derivedmanually. The control set points comprise quantitative parameters thatcan be used as control loop target values. These quantitative parameterscan be divided into QoS parameters and interference parameters. Someexamples of QoS parameters include frame size and frame rate, and frameerror rate (FER) by packet type for video content. Some additionalexamples of QoS parameters include mean opinion score (“MOS”), latency,and jitter for voice content. Additional examples of QoS parameters arethroughput and bit error rate (BER) for data content. The interferencerelated parameters can include, but are not limited to, variousinterference related parameters, such as received signal strengthindicator (RSSI), energy per bit to noise power spectral density ratio(E_(b)/N₀), carrier-to-interference ratio (C/I), and noise floor (themeasure of the signal created from the sum of all of the noise sourceand unwanted signals). The control set points can be used by assessmentmodule 330 of the control system to assess the current state of thecommunication network based on a real-time profile 325 of the RF networkand system environment and to determine whether feedback signals shouldbe generated to adjust the operating state of the network.

The real-time profile module 325 is configured to generate a real-timeprofile of the communication system based on the environment inputparameters received by environment parameter module 320. In anembodiment, the real-time profile comprises quantitative parameters thatreflect current operating conditions of the communication network. Thereal-time profile can comprise QoS and interference related parameters.Some examples of QoS-related parameters include BER, throughput,latency/jitter, protocol-related parameters, and application-relatedparameters. The interference related parameters can include, but are notlimited to, various interference related parameters, such as receivedsignal strength indicator (RSSI), energy per bit to noise power spectraldensity ratio (E_(b)/N₀), carrier-to-interference ratio (C/I), and noisefloor (the measure of the signal created from the sum of all of thenoise source and unwanted signals). According to an embodiment, thereal-time profile can comprise a datagram, spreadsheet, or otherrepresentation of the current operating conditions of the communicationnetwork.

Patterns module 335 is configured to generate patterns that comprise aset of historical quantitative parameter patterns that can be used togenerate feedforward control responses. The patterns can be derived fromthe environment parameters received by environment parameter module 320and the real-time profile generated by real-time profile module 325.These patterns can reflect usage patterns on the network. For example,in an embodiment, the patterns can include specific drivers related tothe date and/or time, a specific application or protocol, and/or aspecific UE.

The control set points generated by control set points module 315 andthe real-time profile generated by real-time profile module 325 can beassessed by assessment module 330 to compare the current operatingparameters of the communication network represented in the real-timeprofile with the control set points to determine whether currentoperating conditions of the network meet the operational requirementsincluded in the policy parameters. If the current operating conditionsof the network do not meet the requirements set forth in the policyparameters, the assessment module 330 can generate feedback signalsindicating that operating parameters of the communication system need tobe adjusted.

The control response module is configured to receive the feedbacksignals from the assessment module 330. The control response module 340(also referred to herein as an optimization module) is configured tooptimize the operating parameters of the communication network in anattempt to meet the requirements of the operator policy. The controlresponse module 340 can be configured to generate control signals basedon the feedback signals received from the assessment module 330. Thecontrol signals fall into two categories: “self” and “remote.” Selfcontrol signals can be applied to the base station itself (the e(H)NB)to change the operating parameters of the base station and remotecontrol signals can be applied to remote devices or components of thenetwork, including UEs, the Core Network, and other e(H)NB to change theoperating parameters of the remote devices or components of the network.

FIG. 4 is a flow diagram of a method that can be used to generate thefeedforward and feedback adjustments of the RF network and systemenvironment using the system illustrated in FIG. 3 according to anembodiment. Updated environment inputs are obtained that represent thecurrent state or new current state of the RF network and systemenvironment (step 410). The environment inputs correspond to theenvironment parameters generated by environment parameter module 320 ofthe communication system. As described above, the environment parameterscan comprise real-time information related to the RF network and systemenvironment obtained from both the Pico cell or Femtocell, subscriberstations, and neighboring cells including macro cells, Pico cells, andFemtocells. A real-time profile is also derived from the updatedenvironment inputs (step 415). In an embodiment, the real-time profilecorresponds to real-time profile generated by real-time profile module325 and can be generated from the environment input parameters obtainedin step 410.

A determination can be made whether the real-time profile matches theset points generated by control set point module 315 (step 420). Asdescribed above, the control set points comprise quantitative parametersthat can be used as control loop target values. The control set pointscan be derived from the policy parameters defined by the networkprovider. If the real-time profile does not match the set points, thereal-time information collected related to the RF network and the systemenvironment indicates that the operating state of the network hasdeviated from the set points that were derived from the networkprovider's operator policy. In response, the feedback adjustment controlsignals can be generated (step 440) to steer the communications networktoward an operating state that is consistent with the policy parameters.

Patterns module 335 can derive patterns from the real-time profile andenvironment input parameters (step 425). In an embodiment, the patternscomprise a set of historical quantitative parameter patterns. Adetermination is made whether a pattern has changed (step 430), and if apattern has changed, the historical quantitative parameter patterns thatcan be used to generate feedforward control responses (step 435) thatcan be used to adjust various operating parameters that can be used tosteer the communication network toward a desired state.

The feedback signals generated in step 440 and the feedforward signalsgenerated in step 435 can be used to generate a set of control signals(step 450) that can be applied to the ‘self’ e(H)NB and remote devices,including UEs, the Core Network and other e(H)NB.

A determination is made whether the network provider has made changes tothe operator policy (step 470). If the network operator has made changesto the policy parameters, new set points can be generated by the controlset points module 315 from the operator policy (step 475) beforereturning to step 410. Otherwise, the method returns to step 410 wherethe environment inputs are collected.

Inputs

The SFF base station can have access to various environmentalinformation that can be used in generating feedback and feedforwardsignals for the control response module 340. This information can bepart of the environment parameters 320 that can be used to generate thereal-time profile generated by real-time profile module 325 and thepatterns generated by patterns module 335. The information can becollected by the SFF base station during step 410 of the methodillustrated in FIG. 4. For example; according to an embodiment, thefollowing environmental input data is typically available (sensed,reported to, etc.) to an SFF base station: (1) signal strength frommacro BTS(s), (2) signal strength from other SFF base station(s), (3)knowledge of whether the macro base stations and the SFF base stationsare co-channel (or adjacent channel); (4) neighboring cellidentification data; and (5) macro network specific information andsystem parameter thresholds. Some examples of additional informationthat can be available to an SFF base station include: DL co-channelcarrier RSSI, DL adjacent channel carrier RSSI, common pilot channel(CPICH) Energy per Chip to Total Noise Power (Ec/No), received totalwideband power (RTWP), public land mobile network (PLMN) ID, cell ID,Local Area Code (LAC), Routing Area Code (RAC), scrambling codes,co-channel CPICH received signal code power (RSCP), adjacent channelCPICH RSCP, P-CPICH Tx Power, macro cell data rate and macro celldead-zone coverage. The macro cell data rate and macro cell dead-zonecoverage can take into account various information, including macrostation load, the number of active SFF base stations, distance of theSFF base stations to the macro station, fading environment, andtime-of-day. The SFF base station can have macro station parameterinformation available to the SFF base station, including target SNR,measured SNR, and received power.

Adjustments

The following item are some examples of the type of parameters that canbe adjusted in step 450 by an SFF base station in response to theenvironment information received via sensing: (1) DL power, (2) UL noiserise target (UL scheduler), (3) UL power, (4) control channel/datachannel power ratio, (5) receiver gain, (6) carrier frequency, (7) DLscrambling code, (8) LAC, and (9) RAC.

Additional Inputs

The SFF base station can have access to additional input information.This information can be part of the environment parameters 320 that canbe used to generate the real-time profile 325 and patterns 335. Theinformation can be collected by the SFF base station during step 410 ofthe method illustrated in FIG. 4. For example, additional inputs such asreal-time traffic metrics can also be available to an SFF base stationand can be used to generate the real time profile 325. For example,real-time traffic metrics, such as the number of active UEs, the numberof idle UEs, indicators of UE mobility and changes in position, theaggregate UL usage, the aggregate DL usage, the Layer 4-7 profile(Voice, video, web, FTP, etc.), the backhaul capacity, and the perconnection BER. The per connection BER data can be obtained beforehybrid automatic repeat request (HARQ) or other retry mechanisms orafter HARQ or other retry mechanisms. In some embodiments, theper-connection BER can be obtained without HARQ. In some embodiments,the per-connection BER data can include statistics on retries.

Historical pattern data (such as patterns 335) can also be available tothe SFF base station, such as time of day data, day of week data, localholiday data, known/unknown UE entering the network, typical usagerates, and typical usage durations. This historical data can be used togenerate patterns 335, which can be used to generate feedforward controlsignals as described above.

Policy input data can also be available to the SFF base station, such asQoS requirements data, priorities data, packet inspection data, andadvanced antenna inputs. This policy information can be part of theoperator policy data 310 described above. The QoS requirements data caninclude delay tolerance data jitter tolerance data, BER/PER tolerancedata, minimum acceptance rate data, and/or other QoS related data. Thepriority input data can include data related to priorities betweenusers, between classes of service, between connections, and/or betweenpackets from the same class of service. Packet inspection data andadvanced antenna inputs data can also be available to the SFF basestation.

Additional Parameters Adjusted

Additional parameters can be adjusted in step 450 in an attempt toremedy oversubscription. In one embodiment, RAN/RF parameters, such asmodulation and coding, subchannelization, time within frame, subchanneland time hopping, multiple-input multiple-output (MIMO) parameters, andbeam forming can be used to remedy oversubscription on the communicationsystem. In another embodiment, traffic policing can be used to remedyoversubscription. Various types of types of traffic policing can beused, including rate limiting, packet blocking, packet dropping and/orintelligent discard. Various techniques for intelligent discard that canbe used to remedy oversubscription are described below.

Optimizing Performance

According to an embodiment, the described systems and methods include anoptimization module to optimize performance by varying extended RAN/RFparameters based on QoS, priority, and policy (also referred to hereinas the “optimization module”). According to an embodiment, theoptimization module can be implemented in a base station, including amacro cell, Pico cell, or Femtocell base station.

In one embodiment, the optimization module is configured to establishthe BER/PER or other quality metric level for each class of service(CoS) or connection. In one embodiment, the quality metric can beprioritized based on known/unknown user equipment, where known userequipment can be given priority over unknown user equipment. The userequipment can include mobile, transient, and stationary subscriberstations. In another embodiment, the quality metric can be prioritizedbased on specific UE identity, and in yet another embodiment, thequality metric can be prioritized based on the application.

According to an embodiment, the optimization module is configured toestablish required/desired throughput for each class of service orconnection. The required/desired throughput can be optionally modifiedbased on whether a UE is known or unknown, based on a specific UEidentity, or based on a specific application.

According to an embodiment, the optimization module is configured to usea standards based approach to derive baseline interference scenario andbaseline RAN/RF parameters.

According to an embodiment, the baseline interference scenario andbaseline RAN/RF parameters can change in real-time as conditions changein the communications network. For example, some of the changingconditions include the number of active/inactive UEs, traffic inneighboring cells, and indicators of change in position of UE, such asround trip delay, RSSI, and tracking via receive beam forming.

According to an embodiment, optimization module can vary the actualscenario and actual RAN/RF parameters in real time as conditions change.For example, in one embodiment, if the BER or quality metric of servicedrops below a threshold, the required physical parameters of service canbe set to be more robust than a baseline value. For example, MIMO can bechanged and beam forming advanced antenna techniques can be applied.Furthermore, modulation and coding changes can be made to improverobustness. Alternatively, a determination can be made whether to exceedbaseline interference scenarios and/or RAN/RF parameters. For example,the determination can be based on sensing data, permissionfrom/negotiation with central controller, permission from/negotiationwith neighboring BTSs, or use spatial multiplexing (beam forming, etc)to minimize interference. Alternatively, a subchannel and time locationin frame (e.g., Orthogonal Frequency Division Multiplexing (OFDM)symbol, time slot, etc.) can be chosen to avoid regular interference.Alternatively, subchannels and time location in the frames can berandomized to statistically avoid interference or selectively increasepotential caused interference, but mitigate through randomization ofimpact.

In an embodiment, if demand exceeds new maximum aggregate throughput (DLor UL, including bandwidth for managing active and idles UEs) thenoptimization module can take steps to mitigate the oversubscription. Inone embodiment, delay tolerant traffic can be delayed to temporarilyreduce demand. For example, one approach includes delaying and bufferingcontent, such as a live video. Live video can be delayed and buffered solong as the variation in delay (jitter) remains within the capacity/timeconstraints of the delay/jitter buffer. In another embodiment,substantial deferral of “download for later use” content is used todecrease demand on the network. For example, in one embodiment,downloads of music and/or video content that is not being consumed asthe content is received (e.g., non-streaming content) can be temporarilydeferred until demand on the network decreases.

In another embodiment, if demand exceeds the new maximum aggregatethroughput, optimization module can selectively discard frames within aservice to reduce demand on the network. For example, some MovingPicture Experts Group (MPEG) frames are less important than others andcan be selectively discarded in order to decrease demand on thecommunication system. In another example, packets having above a minimumacceptable rate for a service can be discarded to reduce demand.

In yet another embodiment, if demand exceeds the new maximum aggregatethroughput, call admission control (CAC) can be used to curtailservices. In some embodiments, services can be curtailed based onpriority, while in some embodiments services can be curtailed based onthe application.

According to an embodiment, the various mitigating actions taken ifdemand exceeds the new maximum aggregate throughput can be reversed whenconditions improve. For example, in one embodiment, hysteresis can beused to smooth reactions.

FIG. 5 is a flow chart illustrating a method that can be implemented bythe optimization module described above to optimizing performance byvarying extended RAN/RF parameters based on QoS, priority, and policyaccording to an embodiment. In an embodiment, the method illustrated inFIG. 5 can be implemented by the control system illustrated in FIG. 3,for example, in the MAC and PHY section. In an embodiment, the method ofFIG. 5 can be implemented in step 450 of FIG. 4.

The method starts at step 501 where in parallel the method determinesRAN/RF aspects of the system (steps 510, 512, and 514) and QoS andtraffic management aspects of the system (steps 520, 522, 524, and 526).

In step 510, the baseline interference scenario is derived and monitoredand baseline for RAF/RF parameter settings is created. In an embodiment,the inputs used to derive the baseline interference scenario can includetypical inputs such as those suggested in the 3GPP TS 25.967, andadditional inputs as suggested in this document, or both. The RAN/RFparameters adjusted can include typical inputs such as those suggestedin the 3GPP TS 25.967, and additional RAN/RF parameters as suggested inthis document, or a combination thereof. In one embodiment, step 510 canbe performed by the assessment module 330.

In step 512, a determination is made in real-time whether any of thefactors influencing the interference scenario and the RAN/RF parametersthat represent the current state of the RF network and the systemenvironment have changed. If these factors have not changed, thisparallel activity continues with the method proceeding to step 530. Ifthe factors have changed, the method proceeds to step 514 where thebaseline interference and RAN/RF parameters are modified to account forthe observed changes, and the method proceeds to decision step 530. Inone embodiment, step 512 can be performed by the assessment module 330,and step 514 can be performed by the control response module 340.

The process of managing the influence on classes of service andindividual connections, and conversely, managing the influence ofindividual services and their associated class of service on theinterface environment can be begun in parallel with step 510. In step520, the maximum or target bit error rate (BER) or packet error rate(PER) (or other quality metric) is established for each class of serviceor each individual service or connection. Each individual service orconnection's actual BER, PER, or other quality metric can be monitored.The maximum or target BER and PER values can be determined based on theoperator policy information 310 provided by the network provider.Additionally, in step 520, the throughput needs or targets of theservice can also be determined. These throughput targets can havemultiple levels, corresponding to multiple levels of QoS that requirediffering levels of throughput. The throughput targets can also takeinto account expected retransmissions based on knowledge of theapplications or the transport mechanisms used at the various layers ofcommunication protocol. In one embodiment, step 520 can be performed bythe control set point modules 315.

In step 522, a determination is made whether the actual error rates,such as the BER or PER, or other actual quality metric exceeds a targetthreshold for the connection determined in step 510. If the BER or otherquality metric exceeds the threshold for the connection, the methodproceeds to decision step 524 to start the process of taking correctiveaction. Otherwise, if the quality metric are no worse than the target,the method proceeds to decision step 530. In one embodiment, step 522can be performed by the assessment module 330.

In step 524, a determination is made whether it is acceptable for theaffected service provider to operate in a manner that can exceed thebaseline interference scenario and baseline RAN/RF parameters, whichcould cause greater interference to services active in neighboringcells. For example, a temporary slight increase in transmission power(e.g., 0.5 dB) can add a tolerable increase in interference to servicesin neighboring cells. If it is acceptable for the affected serviceprovider to operate in manner that can exceed the baseline interferencescenario and baseline RAN/RF parameters, the method proceeds to step 514where the baseline interference scenario and RAN/RF parameters can betemporarily adjusted to accommodate the need for improved QoS for theservice. According to an embodiment, this adjustment may be allowedsolely for the affected service or connection, or can be allowedgenerally for the cell. In one embodiment, step 524 can be performed bythe assessment module 330 and/or the control response module 340.

If in decision step 524 a determination is made that the baselineinterference scenario cannot be exceeded, the method proceeds to step526 where the transmission parameters of the service are modified toachieve the target BER/PER or quality metric without violating thecurrent baseline interference scenario. In an embodiment, this caninclude changes in modulation and coding, transmit power or any of theother adjustable transmission parameters. In one embodiment, step 526can be performed by the control response module 340.

According to an embodiment, when parameters are adjusted, there is apossibility that the bandwidth requirements to meet demand can exceedthe current available aggregate throughput of the cell. Hence, bothparallel paths of the method proceed to decision step 530, where adetermination is made as to whether the demand exceeds the currentavailable aggregate throughput. If the current available aggregatethroughput of the cell is not exceeded, the method returns to step 501and can continuously repeat. Otherwise, the method continues to step 540before continuing to step 501 to repeat. In step 540, a method tomitigate oversubscription is selected and applied. Several methods formitigating oversubscription are described below. In one embodiment,steps 530 and 540 can be performed by the control response module 340.

According to an embodiment, the method illustrated in FIG. 5 can includean uplink instance and a downlink instance that operate independently,for example in a Frequency Division Duplex (FDD) system. Conversely, inother embodiments, the uplink and downlink instances may need to shareinformation in a Time Division Duplex (TDD) system where the uplink anddownlink are on the same frequency and may, therefore, contributeinterference in certain situations. This may be especially true of TDDsystems that adapt the uplink/downlink ratio dynamically.

According to an embodiment, the optimization module can also implementanother method to optimize performance based on historical data toperform anticipated adaptation to reduce potential oversubscription.According to an embodiment, the optimization module can implement thissecond method, which can be used to update the operator policy 310. Ahistory of interference can be built through sensing and/or through theuse of shared metrics received from other network elements (e.g., thecore network, BTSs, UEs). The interference data can be grouped by dateand/or time in order to build a picture of interference patterns forvarious time frames. For example, the interference data can be groupedby the time of day, the day of the week, or by marking the data asholiday or non-holiday. The sensing and/or shared metrics can alsoinclude traffic metrics for the SFF base station's own cell and/or forneighboring cells. The can also include “update with memory trail off”where weighted averaging, exponential averaging, or some other method isused to give higher importance to more recent data.

Preemptive decisions can be made based on the history of interferencethat has been built. For example, a determination can be made whethermore or less strict CAC, policy, and/or power control may help to reducethe likelihood of oversubscription. In an embodiment, a determinationcan be made whether trading off likely robustness versus BER/PER.

According to an embodiment, real time monitoring based on the firstmethod described above and illustrated in FIG. 5 can be used in caseunexpected usage patterns disrupt the predictive interference methoddescribed in the second method. In an embodiment, predictive data can beused for a baseline scenario and the first method can be used forreal-time optimization of the system. In another embodiment, predictivedata generated using the second method can be used to update theoperator policy 310, and the first method can be used to apply theupdated policy.

Intelligent Discard

Referring to FIG. 5, intelligent discard can be used as one of thetechniques of method step 540 to mitigate oversubscription caused bymodification of transmission parameters in step 526 or caused by varyingthe interference scenario and RAN/RF parameters in step 514. This is thereactive form of intelligent discard. Alternatively, knowledge ofavailable intelligent discard techniques may be used to influence thethroughput level target in step 520, the transmission parametermodifications in step 526, and the changes to the interference scenarioand RAN/RF parameters in step 514. This is the interactive form ofintelligent discard. The interactive form may further be made proactiveby using other system information to predict the future oversubscriptionof bandwidth.

According to an embodiment, intelligent discard can be practiced by anyentity of the communications network that performs scheduling. This caninclude the scheduling of downlink bandwidth by any form of base stationincluding macro cell, Pico cell, enterprise Femtocell, residentialFemtocell, relays, or any other form of scheduling. Intelligent discardcan be performed by any form of device that transmits in the uplinkdirection, including user devices, both fixed and mobile, and relaydevices. In an embodiment, intelligent discard can be performed by ascheduling algorithm or module that is implemented in the core network,which centrally directs the actions of devices. In another embodiment,intelligent discard can also be predicatively performed by an entity,such as a base station, that allocates uplink bandwidth for use byanother entity, such as a user device capable of intelligent discard.The base station and the user device can negotiate whether or not theuser device has intelligent discard capability or it may be known basedon the model identification of the user device. According to anembodiment, this approach where an entity, such as a base station, thatallocates bandwidth for use by another entity in the network capable ofintelligent discard, can coordinate with the other entity, such as auser device, can be referred to as cooperative intelligent discard.

Reactive Intelligent Discard

In step 530 of FIG. 5, a determination is made whether or not theapplication layer throughput demand for bandwidth currently exceeds theavailable aggregate throughput or whether a specific session orconnection is exceeding its allocated throughput. For instance, in step520, throughput level targets can be established for the activeconnections being serviced by the base station in question. These targetlevels can be expressed in such quantitative terms as bits per second orbytes per second. In an embodiment, these target levels can includeallowances for retransmissions. Based upon the transmission parametersselected in step 526 and the RAN/RF parameters selected in steps 510 and514, the throughput levels can be translated into required physicallayer resources, such as the resource blocks used in 3GPP LTE, QAMsymbols, OFDM symbols, subchannels, UL/DL ratio, or combinationsthereof. The required physical layer resources can include allowancesfor HARQ or other retransmissions. Once converted to physical layerresources, the throughput level targets or demand can be comparedagainst available physical layer resources as is indicated in step 530.This comparison may return a result indicting that demand for physicalresources currently exceeds available physical resources. In this case,a reduction in physical resource demand is necessary in order to notexceed available physical resources. This in turn determines a necessaryreduction in the current demand for bandwidth at the session, connectionand/or application.

According to an alternative embodiment, other methods can be used todetermine whether the demand for physical resource exceeds the availablephysical resources which can provide an available throughput metric thatcan be used for reactive intelligent discard.

Once a determination is made that application layer throughput demandexceeds available physical resources, intelligent discard can be used instep 540 to reduce the demand while minimizing the need to curtailindividual services and while maximizing the quality perceived by theend user.

For instance, if the demand for resources for a VoIP service exceeds theavailable physical resources by 10%, random (not intelligent) discardmay cause consecutive or near consecutive VoIP packets to be discarded.In contrast, reactive intelligent discard can identify the numberpackets that can be dropped in order to reduce at least a portion of theexcess demand for bandwidth while preserving the perceived quality ofthe call. For example, in one embodiment, in an intelligent discardsystem, the scheduler 278 (see, FIG. 2B) can discard every tenth packet.This could include packets already queued by the scheduler, or packetsas they are being queued, or both. The even distribution of discardedpackets by the intelligent discard method may be less noticeable to theend user than clumping of discarded packets by a random discardalgorithm. According to an embodiment, other patterns can be used toselect the packets to be discarded, so long as the selected patternminimizes the number of consecutive and near consecutive packets thatare discarded.

According to an embodiment, the discard method can also be adjusteddepending on the specific voice protocol and codec being used.Intelligent discard can allow the call to continue with acceptablequality, as determined by a quality score and compared to the operator,system, or local policy.

In another example, in MPEG-2 transmissions, audio packets are moreimportant than video packets, because humans notice changes in audioquality in MPEG-2 transmissions more readily than they notice changes invideo quality. Additionally, the video packets are comprised ofintra-coded frames (“I-frames”), predictive-coded frames (“P-frames”),and bidirectionally-predictive-coded frames (“B-frames”). The loss of anI-frame is typically more detrimental to the quality of an MPEG-2transmission than the loss of a P-frame or B-frame. In fact, the loss ofan I-frame can result in the receiving device being unable to use aP-frame, even if the P-frame is received correctly. So, in MPEG-2intelligent discard may discard P-frames and B-frames preferentially toI-frames and may discard all forms of video frames preferentially toaudio frames.

For MPEG-4 transmission, in addition to the distinction between framesinherited from MPEG-2, there are 11 levels of spatial scalability, 3levels of temporal scalability, and a variable number of levels ofquality scalability depending upon the video application. Fine grainscalability combines these into 11 levels of scalability. In anembodiment, “marking” of packets with information can be performed andthe markings can be used by intelligent discard to allow a fine grainedvarying of quality as available physical resources change.

As with the VoIP example, in the MPEG examples, intelligent discard canperform discard of already queued packets as well as discard upon entryto the scheduling queue. The intelligent discard of a percentage ofpackets can allow more services to be maintained and accepted by thesystem's call admission control (CAC) methods.

In step 540, there may be more than one choice of service that can haveintelligent discard applied to meet the physical layer resourceconstraints. There are numerous criteria that can be used to choose theservice or services to which to apply intelligent discard. For instance,intelligent discard can be applied in a round robin fashion, similarlyimpacting all services or all services within a selected class or set ofservices. Intelligent discard can be applied based on the identity ofthe end user or membership of the end user in some group. For instance,different users may pay more or less for different service levelagreements with the operator of the network. Users with a lower levelagreement may be impacted preferentially to users with a higher levelagreement. Users that are roaming from another network may be impactedby intelligent discard preferentially to users that subscribe directlyto the network. The decision can be based on service type orapplication. For instance, a VoIP call being made via a third partyapplication such as Skype may be impacted preferentially to a VoIP callmade via a VoIP service directly provided by the operator. Which serviceto impact can be determined algorithmically to maximize totalthroughput. The decision on how to apply intelligent discard is based onsystem, operator, or autonomous policy. For instance, a device may havea default policy which may be modified or overridden by a system oroperator policy.

The decision as to which services to impact can be based on relativedegradation, impacting first, for example, those service whose observedquality is least impacted by intelligent discard regardless of therelative quantity of discarded data. To facilitate this, step 540 cancalculate a score for each of the possible throughput levels for thevarious services. These scores represent a relative level of observedquality for each throughput level. These scores may be based onsubjective criteria, such as MOS scores used to score voice quality, ormay be quantitative such as the elimination of a feature from theservice. The scores can be used in step 540 as part of the determinationof which service will have intelligent discard applied and to whatextent. For example, once a set of scores for a set of possiblethroughput levels for services requiring bandwidth, a target bandwidthlevel can be selected for one or more of the services based on the setof scores calculated for the various throughput levels, and packetsassociated with each service can be selectively discarded to reduce thethroughput associated with each of the services to the target throughputlevel associated with that service.

Reactive intelligent discard can be performed in any portion of thesystem that can make a choice regarding transmission or disposition of apacket. For instance, in one embodiment, a base station, pico station,femto station or relay station can include a transceiver fortransmitting and receiving packets. According to a preferred embodiment,these stations can include a MAC layer 276 (see, FIG. 2B) responsiblefor allocation of bandwidth on the uplink and/or the downlink. The MAClayer preferably can contain or be associated with a scheduler (forexample, scheduler 278 in FIG. 2B) and buffers for storing packets priorto transmission. In one embodiment, the intelligent discard techniquesdisclosed herein can be implemented in the portion of the MAC layerresponsible for buffering ad scheduling the transmission of packetswhich is also referred to herein as the scheduler. Alternatively, theequivalent of the MAC scheduler can reside in a core network elementthat performs centralized scheduling, and possibly, buffering. Forexample, in one embodiment, the equivalent of the MAC scheduler could beimplemented to coordinate simultaneous transmission of data, such asbroadcast video or audio, on two or more base stations or other similardevices.

In an embodiment, the intelligent discard techniques can also beimplemented in the MAC scheduler of a user device that schedules andbuffers data prior to transmission in the uplink. According to anembodiment, the core network or base station (or equivalent device) canbe configured to mark packets prior to buffering to facilitate makingeasier discard decisions in the downlink direction. Alternatively, afunction preceding the buffering of packets for uplink transmission bythe user device can mark packets for easier discard decisions by the MACscheduler function in the user device.

Interactive Intelligent Discard

In addition to the previously described reactive intelligent discard,the intelligent discard method can interact with other aspects of thesystem control to gain improved performance. For example, referring nowto FIG. 5, in one embodiment changing a particular RAN/RF networkoperating parameter, such as lowering the maximum transmit power in step510, might benefit neighboring cells by reducing the observedinterference of those cells.

Alternatively, choosing a more robust modulation scheme in step 526 canalso have a similar effect. In a typical system, these changes could beundesirable due to the resulting decrease in available physicalresources, causing the application layer throughput demand to exceedavailable bandwidth. In contrast, in a system employing interactiveintelligent discard, in step 520, a set of throughput levels can becalculated for the active services. The set of throughput levelsrepresents a larger range of physical resource demands when the possibletransmission parameter choices of step 526 and possible RAN/RFparameters of step 510 are considered. Knowledge of these possiblecombinations of quality levels, transmission, and RAN/RF parametersallows the system in steps 510 and 526 to choose parameters that cansubstantially increase robustness of the system, temporarily orpermanently, at the sacrifice of a small amount of quality to one ormore services.

Alternative Implementation of Interactive Intelligent Discard

FIG. 6 is a flow diagram of a modified version of the method illustratedin FIG. 5 that enables other aspects of network operation, such asinterference mitigation and power control, to make use of intelligentdiscard to further optimize system performance. In step 620, rather thancreating a single quality (e.g., BER or PER) and throughput level for aservice or connection (as in step 520 of FIG. 5), a set of throughputlevels and/or range of quantitative quality thresholds (e.g., BER andPER) can be created (605). A score can be applied to each of thethroughput levels. The score represents a relative level of observedquality for each throughput level. According to an embodiment, a scorecan be applied to each of the throughput levels to indicate a relativelevel of observed quality for each throughput level. The scores can bebased on subjective criteria, such as MOS scores used to score voicequality, or the scores can be quantitative, such as the elimination of afeature from the service. The scores can be used in step 640 as part ofthe determination of which server will have intelligent discard appliedand to what extent.

The set of throughput levels and scores, exemplified by data block 605,can be used by step 610, decision step 612, and modified step 614 tomake tradeoffs between service quality and other system operationalfactors. Other steps, such as step 626 can also use the set ofthroughput levels and scores to optimize performance choices. Forinstance, based on the throughput levels and scores, the method in step610 can choose to apply a more robust modulation and lower power thebaseline parameters for a service, with the knowledge that theperformance degradation to the individual service will be small relativeto the reduction in interference caused to neighboring cells. In fact,the change in RAN/RF parameters can be a reaction to a request forinterference reduction from a neighboring cell, or a command or requestfor interference reduction or noise floor reduction from a networkmanagement entity or other centrally located control function, or anautonomous decision to reduce power, interference potential, or someother aspect of network operation. In this way, step 610 and similarfunctions can assess the quality impact implied by the throughput impactresulting from potential alternative actions that can be applied to thepreviously independent task of choosing appropriate RAN/RF parameters.

In a preferred embodiment, an interactive intelligent discard methodimplements the discard function in the equivalent of the MAC layerscheduler (e.g., scheduler 278 in FIG. 2B) and packet bufferingcapability prior to transmission by the transceiver of the station, userdevice, or network function implementing interactive intelligentdiscard. The derivation of sets of quality thresholds, throughputlevels, and scores can be performed by a function that can beimplemented in the core network, the base station (macro, pico orfemto), or user devices and provides the information to the interactiveintelligent discard function which interacts with the buffering andscheduling in the MAC layer to perform intelligent discard. Theinteractive intelligent discard function can also interact with thephysical layer functions, which monitor the RF environment, andinteracts with core network functions or functions on other basestations or network elements to exchange information about the RFenvironments of neighboring cells. A network facing function withininteractive intelligent discard can provide information regarding theservices, user devices, and RF environment to a core network function orto an interactive intelligent discard function on neighboring devices.The interactive intelligent discard method can provide information to anRF or Physical Layer (PHY) control module, which adjusts the RAN/RFparameters for the transmission of certain information packets.

Proactive Intelligent Discard

According to an embodiment, proactive intelligent discard is a techniquefor predicatively performing intelligent discard in anticipation ofoversubscription conditions and for performing the discard before theoversubscription conditions actually occur. Proactive intelligentdiscard can be used to reduce anticipated demand when the anticipateddemand for network bandwidth exceeds anticipated available bandwidth.

Proactive intelligent discard may be applied reactively. For example,expectation of a handover creates expectation of more robust modulationand, therefore, lower throughput per physical layer resource unit as amobile station approaches the edge of a cell. Proactive intelligentdiscard can be used to discard ahead of the actual event, allowingsmoother handovers with controlled discard of data rather than randomloss of data due to congestion.

Proactive intelligent discard can be applied interactively. Forinstance, it may be known from historical data that interference to orfrom neighboring cells increases at a certain time of day (dailycommute, etc.). In proactive intelligent discard, step 612 can determinethat the factors influencing the RAN/RF parameters are about to change,and in step 614 the RAN/RF parameters can be modified based on theassumption that the change will be needed in combination with the set ofthroughput levels and scores created by step 620 in order to proactivelymodify the system parameters so that intelligent discard can preserveoptimal throughput and quality based on the systems policies regardingquality and throughput.

Proactive intelligent discard may be performed based on a variety ofstimuli or trigger events. Some examples of the types of stimuli ortrigger events that can be used to trigger the execution of proactiveintelligent discard include:

(1) Motion—if it is determined that the device is not stationary or isexceeding some speed threshold, proactive intelligent discard mayanticipate the need to perform intelligent discard based on expectationsof motion caused changes in physical parameters that impact throughputavailability.

(2) Expectation of handover—if it is determined that the likelihood ofhandover exceeds some threshold metric, intelligent discard canproactively discard data in a controlled fashion so as to minimize thequality impact of predicted decrease in resources.

(3) Time of day, day of week, or other historical patterns—historicaldata may show that decrease in resources may be expected at predictablepoints in time. Proactive intelligent discard can prepare the system forsmooth transition to lower resources.

(4) Active/inactive user devices in a cell—The number of user devices ina cell may be used to predict fluctuations in demand that would causereactive intelligent discard to take action.

(5) Reserve resources—proactive intelligent discard can aid in servicequality preservation by proactively performing intelligent discard tokeep resources in reserve for other functions such as Call AdmissionControl which may be able to serve more active calls if intelligentdiscard is applied

(6) Changes to Neighbor Cells—information regarding changes in thequantity and configuration of neighboring cells, including but notlimited to: number of neighbor cells, location of neighbor cells, CellOperator, frequency and bandwidth of operation, number of active/idleUEs, RF/RAN parameters.

Additionally, proactive intelligent discard can provide a smoothertransition from one level of discard to another, minimizing the impacton quality of service parameters such as jitter and individual packetdelay.

In an embodiment, proactive intelligent discard can also be used in animplementation where the discard occurs before being needed, applying alower throughput in anticipation of lack of resources. In an alternativeembodiment, proactive intelligent discard can be used in animplementation where the packets to be dropped during the period ofexpected lack of resources are tagged for quick discard, but onlydiscarded in the event that the anticipated lack of resources actuallyoccurs.

In an embodiment, the intelligent discard can also perform the inverserole: accelerating packet transmission into the channel before acapacity limitation comes into effect. This may allow the avoidance of afuture short-term resource constraint.

The historical or other data that is used to create the patterns orhistory that is used to proactively implement intelligent discard cancome from a variety of sources. For example, RF modules can collectinformation regarding the physical environment. In another example, theMAC layer can collect information regarding packet demand andthroughput, and numbers of active or inactive user devices and services.In one embodiment, the information can be processed locally on a deviceto convert the inputs into historical trends, or in an alternativeembodiment, the information can be forwarded to a function in the corenetwork or any other processor for conversion into historical trends andpatterns. The historical trends and patterns can be used locally by adevice or may be shared between devices, such as in the case whereinteractive intelligent discard is applied proactively.

In the following paragraphs various additional embodiments related todiscarding packets are described. Some of the embodiments are describedwith reference to particular standards. However, it will be appreciatedthat the embodiments described herein may be applied to other systemsand standards. It will also be appreciated that the embodiments ofintelligent discard described below may be implemented using the systemsand methods described above including reactive intelligent discard,proactive intelligent discard, and interactive intelligent discard. Forexample, the embodiments described below may be used in conjunction withthe embodiments of intelligent discard describe above with respect toFIGS. 4-6. Further, the embodiments described below may be implementedusing embodiments of the systems described above such as the systemsdescribed with respect to FIGS. 1-3.

In particular, discarding packets according to one or more of theembodiments described below can be practiced within any entity withinthe communications system that performs scheduling. This includes thescheduling of downlink bandwidth by any form of base station, includingmacro cell, Pico cell, enterprise Femtocell, residential Femtocell,relays, or any other form of base station. In another embodiment,discarding packets according to one or more of the embodiments describedbelow can be performed by any form of device which transmits in theuplink direction including user devices, both fixed and mobile, andrelay devices. According to another embodiment, discarding packetsaccording to one or more of the embodiments described below can beperformed by a scheduling algorithm or module housed in the core networkwhich centrally directs the actions of devices or which schedules aservice common to multiple end user devices such as a multicast orbroadcast video service.

According to another embodiment, discarding packets according to one ormore of the embodiments described below can be predicatively performedby an entity such as a base station that allocates uplink bandwidth foruse by another entity, such as a user device. The base station and theuser device can negotiate whether or not the user device is capable ofdiscarding packets according to one or more of the embodiments describedherein, or in some embodiments, whether the user device has intelligentdiscard capability can be determined based on the model identificationof the user device.

According to another embodiment, the prioritization of packets describedbelow can be performed in one device, such as a device performing deeppacket inspection, and may result in a marking of packets where suchmarking is used by another device, such as a wireless base station,which is performing intelligent discard.

FIG. 7 is a functional block diagram of one embodiment of controlresponse module 340 of FIG. 3. As described above, in one embodiment, ifdemand exceeds maximum aggregate throughput for the network, the controlresponse module 340 can respond by selectively discarding frames withina service to reduce demand on the network. In the embodiment of FIG. 7,the control response module 340 comprises a priority/burdendetermination module 744 (“determination module”) and a frame/sliceselection module 746 (“selection module”). As in greater detail below,when frames or slices, the choice of which frame or slice to discard canhave significant effects on the quality of the viewing experience in theresulting video. In one embodiment, determination module 744 determinesa value, e.g., burden or priority, that represents the relativeimportance of that frame compared to other frames. The selection module746 then selects one or more to discard or drop based on the determinedvalue. The operation of the determination module 744 and the selectionmodule 746 are described in greater detail below.

Prioritization for Intelligent Discard

As discussed in part above, in MPEG-2, MPEG-4, and H.264-AVC (MPEG-4Part 10) a video stream is encoded into different types of frames:intra-code frames or I frames, sometimes referred to as Intra frames,predictive-coded frames or P frames, andbidirectionally-predictive-coded frames or B frames. A frame representswhat is displayed on the viewing screen at the frame rate of the viewingdevice. For instance, the NTSC standard used in the United Statesoperates at 29.97 frames per second. The frames are comprised ofmacroblocks. A macroblock corresponds to a 16×16 pixel region of aframe.

The different frame types have different dependencies which can impacterror propagation in the video signal. I frames are encoded such thatthey are not dependent on any other frames. This causes I frames totypically contain the largest amount of data. P frames are encoded basedon an I frame or P frame. This allows encoding of primarily thedifferences between the current P frame and the I or P frame on which itis dependent. This in turn allows P frames to typically contain lessdata than I frames, i.e. they are smaller and consume less bandwidth totransmit. However, an error in the frame on which a P frame is dependentwill propagate errors into the decoding of the P frame even if it isreceived error free. B frames are dependent on both a preceding I or Pframe and a following I or P frame. This dual dependency allows B framesto typically contain less data than either I frames or P frames, butfurthers error propagation. I frames and P frames are often referred toas anchor frames or reference frames.

These dependencies are realized at the macroblock level. I frames onlycontain I macroblocks which are encoded without dependencies onmacroblocks in other frames. P frames may contain I macroblocks or Pmacroblocks, or both. P macroblocks are encoded based on a previous (ornext) I frame or P frame. B frames may contain I, P, or B macroblocks orany combination. B macroblocks are bidirectionally encoded based on botha previous and a subsequent I or P frame.

The pattern of I frames, P frames, and B frames and the associateddecode dependencies are referred to as a group of pictures (GOP) or apredictive structure. The ability to predict or the knowledge of the GOPand the relative error propagation or information carrying potential offrames or portions of frames can be used, as described later, to createrules for discarding packets that take into account the degradation inservice quality such discard imparts to that service and relative toother services.

In addition, H.264-AVC augments the allowable dependencies withmulti-reference predictive structure such that a P frame may bedependent on multiple I or P frames. It also adds hierarchicalpredictive structures which allow B frames to be dependent on other Bframes rather than only I and P frames. Embodiments involving both thebaseline implementation and the augmentations are described below.

A GOP starts with an I frame and may be characterized by two numbers M,the distances between anchor frames (I or P frames), and N, the distancebetween I frames. The gaps between anchor frames are filled with Bframes. A common GOP structure is the M=3, N=12 open GOP shown in 8A.The GOP is considered open because the last B frames of the GOP aredependent upon the last P frame of the current GOP and the I frame ofthe next GOP.

FIG. 8A shows the viewing order of the frames in a GOP. The viewingorder is indicated with the frame numbers 1 through 12. The frame number1′ indicates the first frame in the next GOP. The letter below eachviewing order frame number indicates the type of frame, I, P, or B atthat frame number. The arrows indicate which frame a particular frame isdependent upon. For instance, frame 4 is a P frame dependent upon Iframe 1. Frame 10 is a P frame dependent upon P frame 7. Frames 5 and 6are B frames dependent on P frames 4 and 7. It can be seen that an errorin I frame 1 could propagate through all eleven other frames in the GOPand the last two B frames of the preceding GOP. Worse yet, a loss offrame 1 would make frames 2 through 12 and the last two B frames of thepreceding GOP useless to the decoder. Delaying frame 1 past the time itis to be displayed can have the same effect as the loss of frame 1.Conversely, in this example, loss or erroneous reception of a B framedoes not propagate errors and affects only the individual B frame. Notethat there are modes in H.264 where B frames can be dependent on other Bframes creating a more complex hierarchy, but there will be “leaf node”frames on which no other frames are dependent.

In some systems, control and management section 270 addresses thisproblem of error propagation by applying greater protection to I framesthan P frames and B frames, reducing the impact of poor signal qualityon the decoder's ability to decode and display the video. However, whilebeneficial, this causes the I frames, which are already large, toconsume even more bandwidth. This approach can also cause problems without of order transmission of frames which is not supported by many videodecoders.

In other systems, the control response module 340 can respond bydropping frames. One approach is for the control response module 340 toselect a frame to drop based on the types of frames being transmitted.For example, given the choice between I, P, and B frames, the controlresponse module can be configured to drop B frames before P frames and Pframes before I frames. The decision of which frame amongst several ofthe same type can be made, for example, at random.

In contrast, in other embodiments described herein, the control responsemodule 340 analyzes and takes advantage of the frame dependencies topreserve the quality of the experience (QoE) of the viewer whileintelligently degrading the quality of service (QoS) of the transmissionof the video data to use less bandwidth to react to congestion in thetransmission medium or to allow more video or data services on themedium simultaneously.

In one embodiment, the control module 340 goes beyond mereclassification of I, P, and B frames and determines the relativeimportance of the frames. As described above, there is an importanceattributable to error propagation and the ability for the encoder to usea subsequent frame. But, there is also an element of importance based onthe distribution of frames that have equal error propagation importance.These will both be described with reference to FIG. 8B. After thedetermination of the relative importance of frames, the decision ofwhich frame to drop may be made for a video stream individually.Alternatively, as will be described later, the control response module340 can consider not just the impact of a dropped frame on a singlestream but may consider the relative impact of dropping a frame from oneor the other of two different streams, choosing to drop the one with theleast overall impact.

FIG. 8B shows the same GOP with the same dependencies that was used inFIG. 8A. In addition, in a column with each frame order number and frametype are values indicative of priority, burden, and alternativeformulations of burden. In one embodiment, the priority, burden, andalternative burden values are determined by the determining module 744.The manner in which the priority and burden values are determined by thedetermination module 744 are described in greater detail below.

In some embodiments, the frame priority and burden values shown aresuitable for marking, for instance by a deep packet inspection (DPI)device preceding the transmitting device. Thus, the functionalitydescribed herein with respect to the determining module 744 may beperformed by another device including a device other than a devicecomprising the system described with respect to FIG. 3. In such a case,the selection module 746 uses the previously determined priority burdenvalues to select the frames to be dropped. However, for the purpose ofexplanation, the priority and burden determination functionality isdescribed with respect to determination module 744. In some embodimentsthe described functionality of determination module 744 may be containedand implemented in Real-Time Profile Modules 325 or may advantageouslyhave its functionality distributed between the Environment ParametersModule 320, which may for instance determine that a data stream is avideo stream, the Real-Time Profiles Module 325, which may for instancemake real-time assessment of a video frame's priority, and PatternsModule 335, which may for instance determine the GOP structure throughobservation over time.

In the present description, a lower priority number indicates a greaterframe importance, although it should be clear that the reverserelationship could be used. These priorities indicate a relativeimportance that would allow the transmitting device to intelligentlydiscard frames when faced with congestion or oversubscription of thetransmission medium. Frames with a higher priority number are discardedin preference to frames having a lower priority number.

With respect to the GOP of FIG. 8B, in one embodiment, the I frame isnecessary to be transmitted for all other frames to be useful, so thedetermination module assigns the I frame at frame 1 a priority valueof 1. The P frames chain their dependence off of the I frame, so thedetermination module assigns the first P frame a lower priority (highernumber) than the I frame, but a higher priority (lower number) than thesubsequent P frame. Following this pattern, the determination modulegives the P frames in the GOP the priority numbers 2, 3, and 4respectively. One skilled in the art would recognize that lower prioritynumbers could instead map to lower actual priorities, and higherpriority numbers could map to higher actual priorities.

In one embodiment, since a B frame is dependent upon other frames, thedetermination module assigns the B frame a lower priority (highernumber) than any frames on which they are dependent. This works well forB frames numbered 8, 9, 11, and 12 in the transmission order since theyare all dependent upon P frame number 10 which has priority 4 and is thelowest priority P frame. However, B frames numbered 2 and 3, are lessimportant than P frame 4 as well, even though they don't depend on it.This is for two reasons. First, as previously described, discard of Bframe 2 or B frame 3 does not propagate errors while discard of P frame4 requires the discard of B frames 8, 9, 11, and 12 as well. Second, theP frames are evenly distributed in the GOP. Discarding P frames tends tocause numerous frames in a row to be missing, not merely one in a row.So, in one embodiment, the determination module assigns B frames lowerpriority (higher numbers) than any P frames.

Importantly, all B frames are not themselves entirely equal inimportance. In particular, the importance of a B frame can change basedon whether or not an adjacent B frame is discarded. This occurs because,under certain circumstances, dropping multiple consecutive frames has aworse effect on video quality than dropping frames that are notconsecutive. For example, if B frame 5 were discarded, then subsequentlydiscarding B frame 6 would lead to 2 frames in a row being discarded.However, a subsequent discard of B frame 12 instead would not cause thisto occur.

Advantageously, the determination module can predict and account forthis change in importance. To do so, in one embodiment, thedetermination module assigns an initial priority number of 5 to all Bframes in the GOP. However, where there are consecutive B frames, the Bframe having a higher frame number in the GOP is assigned a lowerpriority (higher number) by the determination module. Thus, in theexample of FIG. 8B the determination module assigns the B framesalternating priorities of 5 and 6 to predict their change in importanceafter a neighboring B frame is discarded. In another embodiment, thedetermination module assigns all B frames the same priority values andthe selecting module 746 could select B frames for discard uniformlyrather than in clusters if and when discard was necessary.

The functionality of the determining module for determining priority canbe summarized as follows: An I frame is assigned priority 1. A P framedependent on frame with priority y, is assigned priority y+1. If z isthe largest priority number of any P frame then either: all B frames areassigned priority z+1, or B frames between two anchor frames areassigned priorities z+1, z+2, z+(M−1), where M is the spacing betweenanchor frames. Alternatively, B frames between two anchor frames areassigned priorities z+(M−1), z+(M−2), . . . , z+1.

In another embodiment, the determination module can determine theimportance of a frame based, at least in part, on how many other framesare dependent upon it. For instance, the I frame at position 1 in theGOP of FIG. 8B has 13 other frames that are directly or indirectlydependent upon it. This includes the other 11 frames in this GOP and,since this GOP is open, the last two B frames of the previous GOP whichdepend on the I frame. The B frames all have 0 other frames dependentupon them. The P frames 4, 7, and 10 have 10, 7, and 4 frames dependentupon them, respectively. This value determination based on dependency isreferred to herein as burden. FIG. 8B shows the burden values for theframes in the GOP.

FIG. 9, describes one embodiment of a method 910 for determining burdenfor frames in a GOP. As described above, the method may be implementedby the determination module 744. In another embodiment, the method maybe implemented by another device or module. For the purpose ofexplanation, the method is described with respect to the decisionmodule. At step 915, the decision module determines the value N, thenumber of frames in the GOP, and M the distance between anchor (I or P)frames in the GOP. In the example GOP of FIG. 8B, N=12 M=3. Thisdetermination can be made by analyzing the frames in the GOP.Alternatively, if these values have previously been determined, thedetermination module can obtain the previously determined values.

At decision step 920, the determining module determines if the currentframe being considered is a B frame. If so, the method proceeds to step925 and the determination module assigns the current B frame a burden of0. In one embodiment, the assigned burden can be stored in a datastructure associated with the frame or the GOP. After the assignment,the next frame in the GOP is made the current frame and the methodreturns to point 927 before decision step 920.

Returning to decision step 920, if the current frame is not a B frame,the method proceeds to step 930. At step 930 the determination moduledetermines the frame viewing order (FVO) of the current frame. Againthis value can be determined by analyzing the frames in the GOP or byobtaining a previously determined FVO. At step 935 the determinationmodule assigns a burden to the current frame equal to the result ofequation 1:

Burden=(N−1)+M−FVO  Eq.1)

After the assignment, the next frame in the GOP is made the currentframe and the method returns to point 927 before decision step 920. Thisprocess continues until the determination module has assigned a burdenvalue for each frame in the GOP.

As shown in FIG. 8B, when determining burden, the determination modulemay alternatively count each frame as burdening itself as well. In thisembodiment, the determination module assigns a burden of 1 to each Bframe. The anchor frames are assigned a burden according to equation 2:

Burden=N+M−FVO  Eq. 2)

Using either burden calculation, the selection module 746 canintelligently select frames for discarding by discarding those with thelowest burdens first. For frames with the same burden, the selectingmodule can discard uniformly, i.e., not clumps of adjacent frames, whendiscard is needed. Alternatively, the selecting module can selectbetween frames of the same burden for discard based on size. Forinstance, two B frames may be of different sizes because one containsmore I or P macroblocks than the other does. If available bandwidthresources allows transmission of the larger B frame, the selectionmodule can preferentially select for discard the smaller B frame overthe larger B frame since it contains less information and its lossshould, therefore, degrade the video quality less than discarding thelarger B frame. However, if available bandwidth resources will notaccommodate transmission of the larger B frame due to its size, theselection module can discard the larger B frame instead of the smaller Bframe.

FIG. 10 illustrates a GOP that does not contain any B frames. The methoddescribed above with respect to FIG. 9 works with these types of GOPssuch as those from MPEG-1 and the H.264-AVC baseline profile, or MPEG-2,MPEG-4, or H.264-AVC GOPs for applications that do not want the extradecoding delay caused by B frames. These frames are inherently not opensince there are no B frames to have bidirectional dependencies. Thedetermination module can use the same methods for analyzing this type ofGOP.

FIG. 11 illustrates another type of GOP three B frames between anchorframes (M=4). The method described above with respect to FIG. 9 workswith these types of GOPs as well. In particular, the determinationmodule can use the same methods for analyzing this type of GOP.Hierarchical and Multi-Reference predictive GOP Structures

As previously mentioned, there exist features within standards such asH.264-AVC which allow for hierarchical or multi-reference GOP predictionstructures. In the case of a hierarchical GOP, B frames can depend onprevious and/or subsequent B frames. The use of multi-reference GOPsallows P frames to depend on one or more P or I frames.

FIG. 12 illustrates one example of a hierarchical GOP. In particular,FIG. 12 shows a 12 frame (N=12) hierarchical GOP structure in viewingorder. The sequence begins with an I-frame, and being an open-GOP,includes references to the I-frame, 1′, of the next GOP. There are no Pframes and a subset of B frames reference other B frames. For example,B4 references both I1 and B7, and B3 references I1 and B4. Thehierarchical set of relationships creates a distinction of purpose andimportance among B frames not seen when analyzing non-hierarchical GOPs.This provides additional information for the determination module toconsider when analyzing the propagation of errors through a GOP and whencalculating frame burden and priority.

For example, in one embodiment, the control response module 340 canrequire that a single B frame be discarded to meet available capacity,then frames B2, B3, B5, B6, B8, B9, B11 or B12 would be preferable toframes B4, B7 and B10 since the former list contains all ‘leaf’ nodeswhose discard would have no effect on subsequent frames. In thisembodiment, the control response module 340 discards a leaf node insteadof a node from which other frames depend.

FIG. 13 illustrates one example of a multi-reference GOP. In thisexample, frame P2 has just one reference frame, I1. However frame P3references two preceding frames, P2 and I1. Frame P4 references P3, P2and I1. These additional references improve the data compression andreduce the size of the later P frames within the GOP.

In one embodiment, the determination module applies an alternativedetermination process to hierarchical and multi-reference GOP structuressuch as the GOPs of FIGS. 12 and 13. In one embodiment, thedetermination module assigns a burden to each frame based on thequantity of frames dependent on it, within a GOP. In making thisassessment, the determination module considers two classes ofdependencies: direct and indirect. FIG. 14 illustrates a set of 4generic frames F1-F4 for the purpose of discussion. Frame F2 isconsidered a direct dependent of Frame F1 since Frame F2 directlyreferences Frame F1 for the decoding of its information. Frame F3 is afirst level, indirect dependent of Frame F1 since Frame F3 referencesFrame F2 directly and Frame F2 references Frame F1 directly. Byextension, Frame F4 is a second level, indirect dependent of Frame F1.

FIG. 15 illustrates a method 1510 for calculating direct frame burden.As described above, the method may be implemented by the determinationmodule 744. In another embodiment, the method may be implemented byanother device or module. For the purpose of explanation, the method isdescribed with respect to the decision module.

At step 1520, the determination module calculates N, the length or sizeof the GOP currently being processed. At step 1530, the determinationmodule assigns a frame number to each frame, beginning at 1 for theleading I frame. In one embodiment, these frame numbers are the frameviewing order of the frames. At step 1540, the determination modulecreates a table, D, of size N by N for storing intermediate burdeninformation. The determination module also creates a weighting vector,X, of size N. In another embodiment, the determination module utilizesan existing table and vector instead of creating new ones. At step 1550,the determination module initializes the table D by zeroing out each ofits values. In another embodiment, the table may have been previouslyinitialized.

At step 1560 the determination module creates a mapping between frameswhich are directly dependent on each other in the table D. Inparticular, for each frame, i, in the GOP, the determination moduleinspects and records the dependencies on all other frames, j, in theGOP. Once a dependency of frame i on frame j is identified, a value ofone is assigned to table D at position (i,j), where i denotes the columnand j denotes the row. For example, if frame 2 is the current frameunder consideration (i) and depends on frame 1 (j), the determinationmodule assigns a value of one in table D at position (2,1). One skilledin the art would recognize that the notation D(i,j) with i as the columnand j as the row is logically equivalent to the notation D(j,i) as longas the notation is used consistently throughout the algorithm.

At step 1570 the determination module determines weighted direct framepriority for each frame. In particular, for each frame j, thedetermination module sums the values of table D(i,j) for all values of Iand adds one. This sum is the number of direct dependencies on frame j.The determination module then multiplies the sum by the weight X(j) fromthe weighting vector X. The resulting values can be stored in a length Nvector by the determination module. The values in this result vectorrepresent the weighted, direct frame priority of the frames in the GOP.

FIG. 18 illustrates a direct frame burden table D. Table D of FIG. 18was generated according to the method described with respect to FIG. 15using the GOP shown in FIG. 12. As shown, each entry (i,j) in table Dindicates whether frame (i) depends from frame (j). For example, sinceframe B3 is dependent on B4 in this GOP, a value of one is located atD(3,4). The resulting weighted, direct priority for each frame j, isalso shown in FIG. 18. The result is the sum of the values for that thatframe, i.e., the sum of the ones in that frame's row of table D, plusone, multiplied by the corresponding weight from weighting vector Xshown in FIG. 16. As shown, Frame I frame I1 has the highest priority.However, in contrast to the burdens of B frames generated by thedetermining module according to the method described above with respectto FIG. 9, the burdens of the B frames shown in FIG. 18 are based uponthe number of dependencies. Accordingly, the determination moduleassigns the B frames burdens of 1, 5 or 7 units.

In one embodiment, the determination module at step 1560 considers eachframe to be dependent upon itself. In this embodiment, at step 1570 thedetermination module does not need to add one to the summation fromtable D.

In another embodiment, direct frame burden table D is replaced with a1×N vector D′ by the determination module. In this embodiment, at step1590, the determination module increments D′(j) by one for each frame ithat is dependent on frame j. The weighted, direct priority for frame jis then calculated by multiplying D(j) by X(j) for each element j.

As described, the method 1505 results in a relative description ofpriority between frames based on at least two factors: (1) the quantityof directly dependent frames and (2) the frame weight. The weightingvector X(j) may be created in a number of ways.

For example, in one embodiment, weighting vector X comprises values suchthat the weight assigned to I frames are larger than P frames, which inturn are larger than B frames. FIG. 16 illustrates a weighting vector Xwith this structure for the GOP shown in FIG. 12. In this example,weighing vector X has a value of 3 for I frames, 2 for P frames and 1for B frames. Thus frame 1, the only I frame, is assigned a value of 3and the remainder of the frames which are all B frames are assigned avalue of 1.

In another embodiment, weighting vector X comprises values based uponthe size of the frames. It some situations, it is advantageous toincrease the priority of larger frames as they most likely containadditional scene detail or motion when compared to smaller frames. Theuse of size in weighting can be done independently of the type of frame(I, B or P) or both size and type of frame may be considered. Forexample, with reference to the GOP of FIG. 12, leaf frames B5 and B6 maycontain important scene detail or motion. In this case, the sizes ofthese B-frames would be larger than the remaining leaf and non-leaf Bframes. The weighting vector X can account for this by increasing theweighting values corresponding to frames B5 and B6.

In one embodiment, the weighting vector is assigned relative weights(for example 1-10) based upon the relative or absolute size of theframes. In one embodiment, the assignment is made using a closed formexpression, a histogram function, or another type of function. In oneembodiment, the assignment function creates weights of either integer orreal number form. The function can be linear or non-linear.

FIG. 17 illustrates a weighting vector X where the weighting valuesincorporate the size of the frames as discussed above. The weightingvector corresponds to the GOP shown in FIG. 12. As can be seen in FIG.17, frame I1 has the largest weight due to its size. Non-leaf nodeframes B7, B4 and B10 have weights larger than 1 due to the largerencoded size of these frames. Because leaf nodes B5 and B6 containsubstantial amounts of detail or motion, their larger size results inweights higher than all other B frames.

FIG. 19 illustrates a method 1902 for determining burden based on bothdirect dependencies and indirect dependencies. As described above, themethod may be implemented by the determination module 744. In anotherembodiment, the method may be implemented by another device or module.For the purpose of explanation, the method is described with respect tothe decision module.

Steps 1905, 1910, 1915, 1920, 1925, and 1930 are similar to thecorresponding steps of method 1505 described in relationship to FIG. 15.For details on the implementation of these steps, refer back to thedescription with respect to FIG. 15. Continuing at step 1935, thedetermination module creates a total burden table T. The determinationmodule copies the values of the table D, generated at step 1930, intotable T. The total burden table T is an N×N table that the determinationmodule uses to determine the effect of both direct and indirectdependencies on burden. For example, with respect to the GOP of FIG. 12,the determination module 744 uses this trace-back approach to accountfor the dependence of Frame B9 on Frame I1 (via B7). In particular, thedetermination module includes the burden of Frame B9 on Frame I1 in theburden value of Frame I1. In one embodiment, the determination moduleuses a trace-back approach in order to account for the indirectdependency of one frame on another.

At step 1940, the determination module sets the values of its twoindices, i and j equal to 1. At step 1945, the determination moduledetermines if the value of table T at position (i,j) is greater thanzero. In this manner, the determination module determines if the frame jhas a dependent frame. If so, the method proceeds to step 1950. In step1950, the determination module determines for the frame, j, using adependent indirect burden table, D, if the frame j itself is dependenton any other frames. If so, then the dependent frame of frame j isincluded in the burden of the frame for which j is a dependent. Forexample, using the GOP referenced in FIG. 12 and table D of FIG. 18, thedirect dependence of frame B9 on B7 is indicated in the direct burdentable D as a value of D(9,7) equal to 1. At step 1250, the determinationmodule determines if B7 itself is dependent on any frame. Thedetermination module performs this process by searching column 7 oftable D for the existence of any entries greater than zero. In thisexample, a 1 is found at table location D(7,1) indicating that frame B7is dependent on frame. Therefore, by definition, frame B9 is a firstlevel, indirect dependent of frame I1. This information is recorded byplacing a 1 into total burden table T at position T(9,1). FIG. 20 showsthe total frame burden table T described with respect to FIG. 19. Theshaded values in table T indicated indirect dependencies captured by thedetermination module utilizing the method of FIG. 19.

Continuing from step 1950, or if the result of decision step 1945 is no,the method proceeds to step 1955. At step 1955, the determination modulecompares the index j to the value N. If j is less than N, the methodproceeds to step 1960. At step 1960 the determination module incrementsthe index j by one and the method returns to decision step 1945.Returning to decision step 1955, if the index j is not less than N, themethod proceeds to step 1965. At step 1965 the determination module setsthe index j equal to 1. Continuing at step 1970, the determinationmodule determines if the index i is less than N. If i is less than N,the method proceeds to step 1975. At step 1975 the determination moduleincrements the index i by one and the method returns to decision step1945. Returning to decision step 1970, if the index i is not less thanN, the method proceeds to step 1985.

The effect of steps 1940, 1955, 1960, 1965, 1970, and 1975 is for thedetermination module to evaluate the dependencies of the GOP using a twolevel ‘nested’ loop. Thus, the determination module explores all of thevalues in direct burden table D for tabulation in total burden table T.

The nested loops are complete after the determination module reaches a‘no’ decision in step 1970. At that point, total burden table T containsthe direct and first level indirect frame relationships between all GOPframes. At step 1985, for each frame j, the determination module sumsthe values of table T(i,j) for all values of i, adds one, and thenmultiplies the result by weight X(j). Note that adding one causes theburden to be non-zero, thereby allowing differentiation throughdifferent weights. For instance if two B frames with no dependencies(same burden) had different weights (e.g. if they were different sizes)not adding one would cause the burdens to be zero causing the product ofthe burden and the respective weights to be zero for both B frames.However adding 1 allows the product of the burdens and the weights to benot equal for the two B frames. The resulting N length vector is theweighted, total frame priority for the GOP. The total frame prioritydetermined by the determination module is shown in FIG. 20 where theweighting vector used is the weighting vector shown in FIG. 16.

The ‘trace-back’ method described with respect to FIG. 19 will calculatethe frame burden based upon the direct dependencies and a single levelof indirect dependency. One skilled in the art will appreciate that thismethod could be extended to include the effect of all indirectdependencies, without limit to the number of dependency levels. In otherwords, the ‘trace-back’ can be designed such that the determinationmodule follows dependencies from root to leaf nodes.

One embodiment to extend the dependency tracking is for thedetermination module to create n−1 additional burden tables T2, throughTn where each burden table represents the cumulative representation ofall dependencies from direct dependencies through nth level indirectdependencies. For example table T3 would represent direct dependenciesplus all first, second, and third level indirect dependencies. In termsof the method of FIG. 19, step 1935-1975 would be performed by thedetermination module for each table Tn. In those steps, the Tn takes theplace of table T and table T(n−1) takes the place of table D. Thedetermination module would finish generating tables once all theelements of a table Tn were equal to all the elements of a table T(n+1),i.e., no new dependencies are identified by the creation of anadditional burden table, T(n+1).

In another embodiment, the determination module can take into accountduplicate dependencies. For example, as depicted in the table of FIG. 18based on the GOP of FIG. 12, the methods described above do not resultin an increased frame burden if more than one dependency path existsbetween frames. For example, Frame I1 is awarded 1 unit of burden due toa dependent frame, B3, despite the fact that there are two dependencypaths between I1 and B3. One is direct; the other is indirect via frameB4. In one embodiment, the determination module accounts for theseduplicate references in order to further amplify the differences amongframe burdens. For example, in the case above, frame I1 would be awardedone additional unit of burden due to the second, duplicate referencebetween frame B3 and I1.

The methods described with respect to FIGS. 15 and 19 consider intra-GOPdependency. In other embodiments the determination module can alsoconsider inter-GOP dependencies present in an open GOP structure.

As described above, multiple approaches can be used to create a usefulweight vector X for use by the determination module in calculating totalframe priority. For example, as previously described above with respectto FIGS. 16 and 17, weights could be assigned based upon frame type (I,P or B), by frame size or some combination of the two.

In another embodiment, the weight vector is extended into the form of aweight table X, of size N×N. In this approach, additional informationabout frame dependency is considered when assigning weight andcalculating priority. In one embodiment, weights are applied todependencies based upon the ‘directness’ of the relationship between theframes being considered. That is, the weight applied to directdependencies is larger than the weight applied to indirect dependencies.In another embodiment, first level, indirect dependencies are weightedhigher than second level, indirect dependencies. Similarly, second levelindirect dependencies are weighted higher than third level, and so on.

For example, weight values of 3, 2 and 1 can be applied to directdependencies, first level indirect dependencies and second levelindirect dependencies, respectively. FIG. 21 illustrates a weight tableX for using this weighting scheme for the total frame burden table T ofFIG. 20.

The weight table X of size N×N can replace weight vector X of size N inStep 1985 of FIG. 19. When using weight table X, the weighted totalframe priority can be calculated for each frame j by summing the productof T(i,j)*X (i,j) for all values of i, from 1 to N.

Advantageously, this approach takes into account that error propagationmay be mitigated by I macroblocks as frame errors propagate through theGOP. Thus the importance of dependencies may be reduced as the level of‘directness’ between frames is also reduced. Slices

In MPEG-2, MPEG-4, and H.264 frames may be further broken into slices.Slices contain an integer number of macroblocks all from the same frame.The dividing of a frame into slices can be implemented by using a singleslice for a frame. A frame can also be divided into j slices, eachcontaining a fixed number of macroblocks. Alternatively, a frame may bedivided into k slices, each containing a variable number of macroblocks.The macroblocks within a slice are not dependent on the macroblocks inother slices from the same frame. If a slice is less than an entireframe, loss of the slice will impact the quality of the video less thanthe loss of the entire frame.

As with frames, there are I slices, P slices, and B slices. I slicesonly contain I macroblocks which are encoded without dependencies onmacroblocks in other frames. P slices may contain I macroblocks or Pmacroblocks, or both. P macroblocks are encoded based on a previous (ornext) I frame or P frame. B slices may contain I, P, or B macroblocks orany combination. B macroblocks are bidirectionally encoded based on botha previous and a subsequent I or P frames.

The same prioritization method, described previously for frames, can beapplied to slices. For instance an I slice that is part of an I framecould be assigned the same burden and priority as the original I frameby the determination module. Similarly, the burden and priority for a Pslice could be assigned the same burden and priority as the original Pframe. The burden and priority for a B slice could be assigned the sameburden and priority as the original B frame.

Since the macroblocks in one slice of a frame can be decoded independentof the macroblocks of the other slices comprising a frame, prioritizingslices allows a finer grain discard during times of congestion or othertimes when a reduction in data rate is necessary or beneficial.

In addition to prioritizing based on burden and frame or slice type, thedetermination module can further differentiate slices with the sameburden based on the relative quantity of each variety of macroblock theycontain. For example, if two P slices have the same burden, the P slicewith more I macroblocks and fewer P macroblocks may be given priorityover a P slice with fewer I macroblocks or more P macroblocks.Alternatively, the fine grain priority adjustment may be based on ratioof I macroblocks to P macroblocks within the slice. A similar finegrained priority adjustment can be applied to B slices based on thecount or ratio of I, P, and B macroblocks. In another embodiment, sinceI macroblocks typically contain more data than P macroblocks and Pmacroblocks typically contain more data than B macroblocks, thedetermination module can adjust priority based on the average size ofthe macroblocks contained in the slice. This can be calculated bydividing the size of the slice in bytes by the number of macroblocks inthe slice.

In one embodiment, the determination module implements a scoring system.For example, the determination module can apply an adjustment thataccounts for the differences in macroblocks in slices of the samepriority level or burden while not allowing slices to cross to adifferent priority level or burden. In one embodiment, the determinationmodule uses a number such that adding or subtracting the number from apriority value moves the priority value less than half way to the nextlower or higher priority. If the difference between priority levels isthe integer value 1, then any number x greater than zero, but less than0.5 could be used. For example, x could equal 0.4.

FIG. 22 illustrates a method 2205 for modifying the priority of a slicebased on the macroblocks in the slice. As described above, the methodmay be implemented by the determination module 744. In anotherembodiment, the method may be implemented by another device or module.For the purpose of explanation, the method is described with respect tothe determination module. Further, in the present description, a lowerpriority numbers means a higher priority. One skilled in the art wouldrecognize that this method can also be used for modifying the priorityof a frame based on the macroblocks in the frame.

At decision step 2210 the determination module determines if a currentslice in the frame is an I slice. If so, the evaluation of the currentslice ends and the next slice is considered. If the current slice is notan I slice, the method proceeds to step 2220. At step 2220 thedetermination module determines a value, y, that is the percentage ofmacroblocks in the current slice that are I macroblocks. Continuing atstep 2230 the determination module adjusts the priority of the currentslice by multiplying x and y and subtracting the product from theslice's current priority. In this manner, the presence of I macro blocksin the slice results in a lower priority number for the slice, i.e., ahigher effective priority.

Continuing at step 2240, the determination module determines if thecurrent slice is a P slice. If so, the evaluation of the current sliceends and the next slice is considered. If the current slice is not a Pslice, the method proceeds to step 2250. At step 2250 the determinationmodule determines a value, z, that is the percentage of macroblocks inthe current slice that are B macroblocks. Continuing at step 2260 thedetermination module adjusts the priority of the current slice bymultiplying x and z and adding the product to the slice's currentpriority. In this manner, the presence of B macro blocks in the sliceresults in a higher priority number for the slice, i.e., a lowereffective priority. In another embodiment, a different value for x canbe used in this step than was used in step 2330 in order to providegreater control over relative priorities. As noted, the determinationmodule can repeat this process for each slice in order to determineadjustments to the slices' priorities.

FIG. 23 illustrates a method 2305 for modifying the priority of a slicebased on the macroblocks in the slice. As described above, the methodmay be implemented by the determination module 744. In anotherembodiment, the method may be implemented by another device or module.For the purpose of explanation, the method is described with respect tothe decision module. Further, in the present description, a lowerpriority numbers means a higher priority. One skilled in the art wouldrecognize that this method can also be used for modifying the priorityof a frame based on the macroblocks in the frame.

The steps 2310, 2320, 2330, and 2340 are identical to the correspondingsteps of method 2205 of FIG. 22. For details of the implementation ofthese steps refer to description of the corresponding steps with respectto FIG. 22. Continuing at step 2350, the determination module determinesa number, z, that represents the percentage of macroblocks in thecurrent slice that are P macroblocks. Continuing at step 2360, thedetermination module adjusts the priority of the current slice bymultiplying x′ and z and subtracting the product to the slice's currentpriority. In this step, x′ is calculated similar to x, but allows adifferent adjustment to be applied for P macroblocks than for Imacroblocks in the B slice.

One skilled in the art would appreciate that other adjustments may bemade to a slice or frame priority based on the number, percentage, orsize of I, P, and B macroblocks.

Some video standards such as H.264-AVC allow redundant slices. Redundantslices carry redundant information in case an original frame is lost ordamaged. For the purposes of prioritized discard, redundant slices areassigned a priority level lower than that of B slices since theygenerally will not be needed by the decoder.

Some video standards such as H.264-AVC allow switching slices that alloweasier or faster switching between video streams. SI slices allowswitching between completely different streams. In one embodiment, if nostream switching is expected, SI slices are assigned a lower prioritythan B frames since they generally will not be used by the decoder.However, if switching streams is expected to be common, such as in amulticast or broadcast system streaming multiple video streamssimultaneously, policy may dictate the priority of SI slices, and theymay be prioritized above B or P slices, but typically not above Islices. Similarly, SP slices allow easier or faster switching betweenstreams of the same video content encoded at different rates orresolutions. Unless such a switch is to be made, SP slices are assigneda lower priority than B slices. However, if such a switch is to be made,SP slices are assigned a priority in the same manner as P slices.

Both SI and SP slices can be used for video playback and managementfunctions under the control of a human viewer. For example, a person maychoose to fast forward or rewind the content currently being viewed. Aperson may choose to change viewing streams (or ‘channels’ as they arecommonly described in broadcast video) or adjust the displayedresolution and/or screen size once such playback has begun. Depending onthe video standard and encoding methods, these viewer requests mayinvolve the use or increased use of SP and/or SI frames. Since usercontrol response time is a critical performance metric for videotransport and playback systems, the importance of SP and/or SI frames issubstantially higher during such periods of user requests.

In one embodiment, dynamic prioritization for SI and SP frames is usedto detect user requests and respond by increasing the frame priority forSI and SP frames. This can be implemented, for example by the controlresponse module 340. The request detection can take several forms. Oneapproach is to monitor uplink control traffic (traveling in the oppositedirection of the video traffic) in order to detect specific userrequests. Another form establishes a baseline frame rate for SI and SPframes, measured for example using frames per second, and to detectperiods when the current SI or SP frame rate exceeds this baseline rateby some predetermined threshold, for example by a factor of 2x. Once auser request has been detected, the priority level for SI or SP framesis raised and can even surpass the priority level currently assigned toI frames. The increased priority level can be maintained for theduration of user request(s) plus some configurable timeout period.

Data Partitioning

In some video standards such as H.264-AVC, the data in a slice may befurther arranged into data partitions. For example, a slice in H.264-AVCmay be partitioned into three data partitions. Data partition 1 containsthe slice header and the header data for each macroblock. Data partition2 contains the data portion of I or SI macroblocks from the slice. Datapartition 3 contains the data portion of P, B, and SP macroblocks fromthe slice. These data partitions may be transported separately. Datapartitions 1 and 2 are both necessary to recover the I macroblocks, sothey may be linked together for discard prioritization by thedetermination module. The priority of partitions 1 and 2 can have theirpriority adjusted by applying the slice priority adjustment method todata partition 2 and assigning the same priority to data partition 1.Alternatively, since data partition 1 is also necessary for use of datapartition 3, data partition 1 can be assigned a priority that isslightly higher than the priority of data partition 2. The priority ofdata partition 3 can have its priority adjusted by applying the slicepriority adjustment method to data partition 3.

Once video frames are prioritized, for example, using the techniquesdescribed above, a scheduler (e.g., scheduler 278 in FIG. 2B) in atransmitting device such as a wireless base station on the downlink or asubscriber station (e.g., a wireless fixed, portable, or mobile userdevice) on the uplink may use this information to intelligently discardduring periods of congestion or to optimize the admission of calls andservices into the system. In these systems, video frames are typicallycarried in data packets such as Internet Protocol (IP) packets.

FIG. 24 is a functional block diagram of an embodiment of a system thatuses prioritization to determine which data packets to discard when theavailable bandwidth is less than that which is required to transmit allpackets to all recipients. The system can degrade certain services bydropping selected packets associated with those services in a mannerthat minimizes the degradation of the user's experience. In oneembodiment, the previously described prioritization scheme for video isused. In one embodiment, the depicted system is implemented in the MAClayer 276 (see FIG. 2B) of a base station or access point or in thescheduler of a subscriber station. However, as noted below, thedescribed functions can be implemented in different devices. In oneembodiment the prioritization and marking module (“determinationmodule”) 2410, scheduler queues 2420 and the scheduler 2440 implementthe functionality described above in connection with the ControlResponse Module (optimization module) 340 of FIG. 3.

The prioritization and marking module 2410 prioritizes packets fordiscard. This can use the previously described methods for prioritizingvideo packets, but one skilled in the art would recognize that differentmethods may be used for different types of data streams, e.g. videoversus voice. The prioritization and marking module 2410 can be locatedin the transmitting device itself, or may be located in a separatedevice, such as a DPI device, that marks the frames, for instanceappending or inserting bits to the packets carrying the video frames,prior to transferring them to the transmitting device. In one embodimentof the system depicted in FIG. 24, the prioritization and marking module2410 implements the functionality described in connection with thePriority/Burden Determination Module 744 of FIG. 7. Similarly, in oneembodiment of the system depicted in FIG. 24, the scheduler 2440implements the functionality described in connection with theFrame/slice Selection Module 746 of FIG. 7 and can therefore also bereferred to as a selection module. This prioritization allows for theevaluation of the trade off between dropping packets associated with atype of service (e.g., video or voice) and the corresponding amount ofdegradation to that service as is more fully described below. Afterprioritization, the packets are transferred to the scheduler ortransmission queues 2420.

Discard may occur as the packets (e.g. video frames) are being queued bythe prioritization and marking module 2410 as represented by the flowdiagram in FIG. 25, or packets may be discarded by the scheduler 2440after they are placed in the queues 2420 used by the scheduler asrepresented by the flow diagram in FIG. 26. As shown in FIG. 25, packetsreceived (step 2510) by the prioritization and marking module, forinstance from a core network 102 over a backhaul 170, are evaluated bythe prioritization and marking module 2410 to determine whether theymeet the criteria for discard (step 2520). Alternatively, this functioncould be implemented in the scheduler. Packets that meet the discardcriteria are discarded at a step 2540 and packets that do not meet thediscard criteria are placed in the queue(s) 2420 of the scheduler at astep 2530. Flow then returns to step 2510. If packets are discarded asthey are queued as shown in FIG. 25, then marking of the packets by theprioritization and marking function 2410 is not required.

As shown in FIG. 26, the discard process can also be performed forpackets that are already queued in the queue(s) 2420 of the scheduler.At a step 2610 the scheduler waits for packets to be received in itsqueue(s). Checking for received packets may be periodic, for instancedriven by a 1 millisecond timer, or may be aperiodic, for instancedriven by the receipt of a packet to be queued. After packets are in thequeue(s), the scheduler waits for a time to schedule a packet fortransmission at a step 2630. When it is time for the scheduler toschedule a packet for transmission, one or more packets are extractedfrom a queue at a step 2640. At a step 2650 the extracted packets areevaluated against the discard criteria. In one embodiment, if the packetis a video packet, the above prioritization scheme may be used with themethods discussed below to determine eligibility for discard. Packetsthat meet the discard criteria are discarded at a step 2660 and packetsthat do not meet the discard criteria are scheduled for transmission ata step 2670. Flow then returns to step 2630. Alternatively, afterpackets are queued, in response to a stimulus such as congestion, aninspection of all packets within one or more queues is made wherebythose packets which meet the criteria for discard are removed whileleaving those that do not meet the criteria for discard. The packetsthat are not discarded would be scheduled for transmission at theappropriate time. One skilled in the art would understand that themethods of FIGS. 25 and 26 may be used in combination. That is, somepackets can be discarded at queue ingress while other packets are markedor otherwise selected for discard at queue egress.

The decision of which packets to discard is influenced by the discardlevel which is a function of data rate, quality and system resources asdescribed later. The discard level can be determined by (or based uponinformation received from) a system state module or function that isaware of the overall system state, for example, the call admissioncontrol (CAC) module 2460 shown in FIG. 24. The CAC module resides on adevice responsible for determining whether new calls or services shouldbe allowed. This can be a base station or the equivalent, and it can bea device in the core network such as a serving gateway. The CACfunctionality may be distributed between multiple network devices. TheCAC functionality may make use of PHY parameter information from thetransmission module 2450, allowing it to know the conversion from bytesto physical resources for the various services.

The scheduler module 2440 determines which data packets should betransmitted over the communications network, in what order and when. Thepriority of the packets may be expressed to the scheduler 2440 basedupon queue assignment, their order in the queues 2420, by markingscreated by the prioritization and marking module 2410 or somecombination thereof. If packets are discarded as they are removed fromthe queues (as explained above in connection with FIG. 26), thescheduler 2440 performs this discard based on information from sourcesincluding queue assignment and order and marking created by theprioritization and marking module 2410, discard levels and the overallresource availability from a CAC module 2460 or similar module, and PHYparameters from the transmission module 2450. In a preferred embodiment,the scheduler resides on the transmitting device such as a base stationor equivalent, but can reside on a device that provides the schedulinginformation to the transmitting device.

The transmission module 2450 is responsible for transmission of thepackets across the physical medium such as radio waves over the air.This module can be implemented in the PHY layer 280 of FIG. 2B or itsfunctionality can be split between the PHY layer and the Modem 272. Inaddition, the transmission module can make decisions regarding the PHYparameters, such as modulation and coding scheme, necessary for reliabletransmission and reception. These parameters affect the capacity of thesystem and can be provided to other modules that may need them such as aCAC module 2460 and scheduler 2440.

In a wireless system with a physical layer (PHY) that adapts toenvironmental conditions, the bits per second capability of the systemcan change as a function of the PHY parameters such as modulation schemeand forward error correction (FEC) coding. The bits per secondcapability of the system can also be affected by fluctuations inretransmission rates due to packet errors. In a broadband wirelesssystem these fluctuations in the bits per second capacity of the RF linkcan impact all services on the link, not just those to or from the userdevice experiencing PHY parameter changes. This can create congestion ifthe demand for bandwidth exceeds the new bits per second capacity of thesystem. It can also cause an oversubscription situation. That is to say,it can cause a situation where chronic congestion is likely to occurbecause the total time-averaged demand of admitted services exceeds thecapacity of the RF link.

In systems where services have a single priority for all packets carriedon the service, this chronic congestion can lead to some services beingterminated. Alternatively, packets from services can be discarded onlylooking at the relative priorities of the services, not the prioritiesof the individual packets carried on the service or the impact ofdiscard on different applications.

For video, however, prioritizing the individual packets based on thetype of video frame they transport allows the system to intelligentlydiscard packets based upon the relative importance of individualpackets. Such a system can also make a quantitative estimate of thequality with which a user will experience the video stream after packetdiscard. Within the bounds of operator policy, a wireless network cangracefully degrade a video service rather than terminate the service ordegrade the service in a manner that provides unacceptable quality aswould be the case with random discard.

While optimal encoding of video can produce a highly variable bitstream, the variability is typically bounded. There are two reasons forthis. First, many legacy systems, such as cell phone systems, expect aconstant bit rate (CBR) over a given period of time. To ensure thedecoder does not experience buffer overflow or underflow, a CBR encodermay make an a priori, non-optimal choice for the size of I frames, Pframes, and B frames. This then allows buffer sizing at the encoder anddecoder based on, for instance, the GOP and the frame dependencyrelationships it contains. Second, even in systems that implementvariable bit rate (VBR) encoders and decoders, the bit rate variabilityand frame sizes are usually bounded to prevent buffer overflow orunderflow.

The I, P, and B frame sizes may vary in a VBR video stream, but can bebounded by maximum values that are similar to the relationship used forCBR video streams. Alternatively, the average size of different frametypes in a VBR stream may be calculated based on historical data for thevideo stream, for instance by using an exponential average or othertechniques known to one skilled in the art. This method can also be usedfor CBR streams for which the entity interested in the bandwidth demandof the stream does not know the frame size bounds. The frame size boundor historical average frame size can then be used to estimate thebandwidth occupied by each type of video frame in a GOP.

Similarly, the GOP may be known a priori or may be detected based onreceived frames. The determination of the frame sizes and the GOPstructure allows calculation of the bandwidth needed for a GOP and,therefore, the bit rate of the video stream. Variations in the bit rateand average frame sizes may be quantified by calculating the variance orstandard deviation.

FIG. 27 is a flow diagram of a method for determining the GOP structureand average size. In one embodiment, the method is implemented by theprioritization and marking module 2410. At step 2710 a video frame isreceived. At step 2720, the type of the video frame is determined. Thisdetermination may be made by inspecting the header or contents of thevideo frame or the transport packet in which it is contained.Alternatively, it may be heuristically determined by a method such ascomparing its size to the size of other packets in the same stream andto the average frame size for each frame type, once established. If theframe is an I frame, flow proceeds to step 2730 where the average sizeof I frames for this video stream is updated, for instance usingexponential averaging. From step 2730 flow proceeds to step 2740 wherethe number of frames since the most recent I frame is determined. Flowthen proceeds to step 2790 where the data collected and calculated insteps 2730 and 2740 are used to update the knowledge of the GOPstructure and the average GOP size. If at step 2720 the video frame isdetermined to be a P frame, flow proceeds to step 2750 where the averagesize of P frames for this video stream is updated. Flow then proceeds tostep 2780 where both the number of frames since the most recentlyreceived anchor frame is determined and the type of anchor frame (I or Pframe) is also determined. Flow then proceeds to step 2790 where thedata collected and calculated in steps 2750 and 2780 are used to updatethe knowledge of the GOP structure and the average GOP size. If at step2720 the video frame is determined to be a B frame, flow proceeds tostep 2770 where the average size of B frames for this video stream isupdated. Flow then proceeds to step 2780 where both the number of framessince the most recently received anchor frame is determined and the typeof anchor frame (I or P frame) is also determined. Flow then proceeds tostep 2790 where the data collected and calculated in steps 2770 and 2780are used to update the knowledge of the GOP structure and the averageGOP size.

FIG. 28 is a graphical representation 3000 of an example of relativeframe sizes for an N=12, M=3 GOP. In this example, P frames average halfthe size of I frames and B frames average one fifth the size of Iframes. This is an example only and other relative frame sizes can occurdepending upon the encoding. The frame size counter on the left of FIG.28 is in units of 1000 bytes. In this example, I frame 3001 averages10,000 bytes in size, P frames 3015(1)-3015(3) average 5000 bytes insize and B frames 3005(1)-3005(8) average 2000 bytes in size. This givesan average of 41,000 bytes per GOP. Since the GOP in this example is 12frames in duration and a typical frame rate for display on a mobilephone is 25 frames per second, this gives an example average data rateof approximately 85,417 bytes per second or 683 kilobits per second.This is only an example, and one skilled in the art would know thatother data rates are both possible and common. When an event happensthat causes there to be only 79,000 bytes per second of bandwidthavailable for this service, older systems would terminate the service,unacceptably delay the video frames, or randomly drop frames. All ofthese scenarios are likely to result in unacceptable quality for theuser.

However, if the frames are prioritized within the video service, theycan be intelligently discarded, based on a combination of burden or asimilar metric and a desire for uniform spacing of discards amongstframes of the same priority. To minimize the impact to the quality ofthe video stream, it is desirable to discard the minimum number offrames necessary to fit within the new bandwidth constraint. Bydiscarding 25% of B frames in a uniform fashion demand can be lowered to77,083 bytes per second, fitting in the available bandwidth in theexample. To further reduce the probability of degradation of the videoquality, the B frames can be discarded uniformly thus allowing, forinstance, interpolation systems in the video decoder to minimizerecovery artifacts. In this example, B frames 3005(2) and 3005(6) arediscarded as shown in FIG. 29. Alternatively, discarding B frames3005(4) and 3005(8) gives a similarly uniform distribution of discards.These choices can be predetermined using the previously describedprioritization method.

Quality of video streams may be measured using video mean opinion scores(VMOS) or alternative quantitative methods. The degradation in VMOSattributable to discard policies can be predicted based on measurementswhich can be refined over time.

As seen in FIG. 30 and FIG. 31, using the prioritization of packetswithin a video stream as discussed earlier, progressively more framescan be discarded if needed, while minimizing the degradation of thevideo quality. How much the quality is allowed to be degraded before aservice is terminated can be controlled by operator policy or userpreferences.

The table below demonstrates that the foregoing techniques provides asmany possible bandwidth demand or discard levels as there are frames ina GOP. Additionally, other finer grain discard levels may be achieved bydiscarding portions of frames, such as slices, or by using inter-GOPtechniques such as discarding one B frame every other GOP or discardingtwo B frames every 3 GOP.

Average % reduction bytes of in bandwidth VMOS Discard level data in GOPdemand degradation no discard 41,000   0% none discard 1 B frame 39,000 4.9% Δ1 discard 2 B frames 37,000  9.8% Δ2 discard 3 B frames 35,00014.6% Δ3 discard 4 B frames 33,000 19.5% Δ4 discard 5 B frames 31,00024.4% Δ5 discard 6 B frames 29,000 29.3% Δ6 discard 7 B frames 27,00034.1% Δ7 discard 8 B frames 25,000 39.0% Δ8 discard 1 P frame (and all20,000 51.2% Δ9 8 B frames) discard 2 P frames 15,000 63.4% Δ10  discard3 P frames 10,000 75.6% Δ11 

Each of these discard levels degrades or decreases the quality of thevideo service. But, just as encoder and decoder performance can bequantified by metrics such as VMOS, the degradation due to intelligentdiscard can be quantified using these metrics. This can be accomplishedby measuring VMOS degradation due to discard as described herein for anumber of common GOP, and deriving metrics for use in estimating VMOSdegradation.

In this way, a video service can have an associated set of bandwidthrequirements each paired with a quality metric. Operator policy or userpreferences can indicate the quality metric value where the service isconsidered unacceptable and is terminated rather than further degraded.For instance, a policy can be adopted that loss of more than every otherB frame is unacceptable. In this example, shown in FIG. 29, four Bframes per GOP could be discarded accounting for a 19.5% reduction inbandwidth demand. If a further reduction in bandwidth were necessary,the service would be terminated or suspended or alternatively, adifferent service may be terminated, suspended or have discard appliedto reduce its demand, reducing overall system demand. The discard couldbe performed as previously shown in FIG. 25 or FIG. 26.

One skilled in the art would understand that the quality metric valuemay be applied differently to individual video streams, video streamapplications (e.g. Youtube versus Netflix), users, user SLA categories,classes of service, scheduler queues or combinations thereof.

The relationship between rates and VMOS can be used for admitting newservices. For instance, if a user wanted to initiate a video streamthat, as in the previous example, required 85,417 bytes per second ofbandwidth, but only 79,000 bytes per second were available, the systemwould know that the service could still be admitted, but at the degradedquality provided by discarding 2 B frames per GOP to achieve 77,083bytes per second of bandwidth demand. If that degradation was acceptableto operator policy and user preferences, the service would be admittedrather than denied. Alternately, if a policy allowed a different serviceto have its bandwidth demand reduced, the system could apply a bandwidthreduction to that other service freeing up bandwidth to allow the newservice to be admitted. This call admission control (CAC) method isrepresented in the flow diagram depicted in FIG. 32 and in oneembodiment is implemented by the Call Admission Control module 2460shown in FIG. 24.

At step 3205, a request for a new service is received by the system.This request may come from a user device requesting a service or maycome from an external entity initiating the service, for example a videoconferencing call between a room full of people and a participant on amobile handset can be initiated by the user of the wireless handset ormay be initiated using the landline attached to the conference roomvideo conferencing equipment. At step 3210, a check is performed todetermine if there are sufficient system resources to admit the service.Call admission control is commonly used in many communications systemsand one skilled in the art would understand the standard methods for theparticular communication system they were concerned with. For example,U.S. Pat. No. 7,529,204 (hereby incorporated by reference) describescall admission control for use in communication systems that employadaptive modulation. If there are sufficient resources, the service isadmitted in step 3215. If at step 3210 it is determined that there areinsufficient resources to admit the service, then flow continues to step3230 where a check is performed to see if the service can be admitted ina degraded form. If the service can be admitted in a degraded form, flowproceeds to step 3235 where the service is degraded, for example adiscard level is chosen such that 25% of B frames will be discarded,after which the service is admitted in step 3240. If step 3230determines that the service cannot be sufficiently degraded, within thebounds of policy, to fit within the resource constraints, flow proceedsto step 3270 where a determination is made whether a different serviceor some combination of services, possibly including the new service, canbe sufficiently degraded to allow the new service to be admitted. If atstep 3270 it is determined that a collection of services can besufficiently degraded, flow proceeds to step 3275 where the identifiedservices are degraded and the new service is admitted in step 3280. Ifat step 3270 it is determined that no collection of services can besufficiently degraded, flow proceeds to step 3290 where the new servicerequest is rejected.

In alternative embodiments, the set of steps 3230, 3235, and 3240 may beremoved from the method. Conversely, steps 3270, 3275 and 3280 may beremoved from the method.

This described CAC method may run in a wireless base station or theequivalent in another network, such as the head end in a DOCSIS cablemodem system. Alternatively, it may run on a management entity in thecore network, such as a serving gateway.

While the above CAC method is described in the context of video servicesthat may be degraded using the methods of this invention, one skilled inthe art would understand that it applies to all services that may bedegraded, such as a data service that has a minimum guaranteed rate butis allowed to burst to a maximum data rate or a Voice over IP (VoIP)service for which policy would allow a certain percentage, for example5%, of the packets to be lost or discarded.

In addition to setting degradation levels for services to allow a newservice to be admitted, a similar approach may be used in system such asWiMAX and LTE where system resources may vary dynamically due tochanging environmental conditions and their effect on the choice of PHYparameters such as modulation, coding, and MIMO mode. FIG. 33 is a flowdiagram of a method that allows graceful degradation of services inresource reduction situations, avoiding random discard or excessivesuspension or termination of services. In one embodiment, the method isimplemented by the call admission control module 2460 shown in FIG. 2B.

At step 3310 an event occurs which reduces system resources and thereduction in system resources is recognized. This could be, for example,caused by a mobile handset moving to the edge of a cell and requiringmore robust coding and modulation. Flow proceeds to step 3320 where acheck is performed to determine if there are still sufficient resourcesfor the current services in their current states. If at step 3320 it isdetermined that there are sufficient resources for the current services,flow proceeds to step 3330 where no action is taken. If step 3320determines that there are no longer sufficient resources for the currentservices in their current states, flow proceeds to step 3340. At step3340 a check is performed to determine if some combination of servicesmay be degraded to allow continued operation of services within the newresource constraints. This determination can proceed as discussed inconnection with step 540 of FIG. 5. In general, the system determineswhether some combination of services may be degraded through theselective dropping of packets associated with some combination ofservices which imposes the overall minimum service degradation accordingto predetermined criteria and which does not exceed a maximum allowabledegradation to any service. If there is a combination of services whichmay be degraded to allow continued operation of services, flow proceedsto step 3350 where those services are degraded. If there does not exista combination of services which may be degraded to allow continuedoperation of services, flow proceeds to step 3360 where services areidentified for suspension or termination. The choice of which servicesto suspend or terminate may be based upon many factors including amountof resources freed, priority of service, contracted service levelagreement, and link quality to the user of the service. Step 3360 mayoptionally combine degradation of some services with suspension ortermination of others to minimize the number of services that requiresuspension or termination.

One skilled in the art would understand that degradation of services canbe relaxed and suspended services can be resumed after an increase insystem resources such as when a mobile handset leaves the cell orchanges to a more efficient modulation and coding scheme.

For VBR services, the preservation of quality and the efficient use ofresources can be even greater. For VBR streams, the upper limit of framesize may be bounded, but the average frame size may be smaller. Duringsome GOPs, many frames may be smaller. This can allow for some framesbeing retained that would necessarily be discarded in the CBR case. Toallow for this, the preferred embodiment uses egress discard as wasdescribed with reference to FIG. 26. In the method shown in FIG. 26,step 2650 is augmented to allow a packet to be scheduled fortransmission at step 2670 even if at step 2650 it is determined that thepacket meets the criteria for discard if there are sufficient systemresources. Such an event would occur, for instance, if the average sizeof GOP, in bytes, was sufficiently less than average at the time,creating less demand than expected when the discard level for theservice was set.

Statistical multiplexing of VBR video streams in a broadband systemfurther allows one stream to benefit when another stream has atemporarily low bandwidth demand. For instance, in one embodiment theaugmented step 2650 of FIG. 26 allows a video frame that step 2650determined meets the criteria for discard from one service to bescheduled for transmission by step 2670 if a different service or thecombination of all services has used fewer system resources that wasexpected when the discard level was determined.

The priority scheme described can be used with schedulers that make lastminute decisions to maximize frame retention or with schedulers thatthat proactively discard in anticipation of congestion. The priorityscheme can also be used with a scheduler that uses proactive discard toget close to the target bandwidth consumption for a service yet staysabove the target bandwidth consumption, and then performs last minutediscard to maximize statistical multiplexing gains.

One skilled in the art will appreciate that the prioritization describedabove may be used for purposes other than intelligent discard, forinstance enhancing Call Admission Control by providing additionalinformation regarding how much data from a video service may bediscarded while maintaining a required service quality, thus allowingmore services to be admitted than would be possible without thisinformation.

As described above, the packet discard and frame analysis describedabove may be performed by communication devices or systems including,but not limited to, an access point, base station, macro cell, Picocell, enterprise Femtocell, residential Femtocell, relay, small formfactor base station, subscriber station, core network system or otherdevice. In some embodiments, these communication devices may compriseone or more processors, transceivers, antenna systems, andcomputer-readable memories or media that operate to accomplish thefunctionality described herein.

Those of skill will appreciate that the various illustrative logicalblocks, modules, units, and algorithm and method steps described inconnection with the embodiments disclosed herein can often beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, units, blocks, modules, andsteps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular system and design constraintsimposed on the overall system. Skilled persons can implement thedescribed functionality in varying ways for each particular system, butsuch implementation decisions should not be interpreted as causing adeparture from the scope of the invention. In addition, the grouping offunctions within a unit, module, block or step is for ease ofdescription. Specific functions or steps can be moved from one unit,module or block without departing from the invention.

The various illustrative logical blocks, units, steps and modulesdescribed in connection with the embodiments disclosed herein can beimplemented or performed with a general purpose processor, a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a field programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor can be a microprocessor,but in the alternative, the processor can be any processor, controller,microcontroller, or state machine. A processor can also be implementedas a combination of computing devices, for example, a combination of aDSP and a microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm and the processes of a block ormodule described in connection with the embodiments disclosed herein canbe embodied directly in hardware, in a software module (or unit)executed by a processor, or in a combination of the two. A softwaremodule can reside in RAM memory, flash memory, ROM memory, EPROM memory,EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or anyother form of machine or computer readable storage medium. An exemplarystorage medium can be coupled to the processor such that the processorcan read information from, and write information to, the storage medium.In the alternative, the storage medium can be integral to the processor.The processor and the storage medium can reside in an ASIC.

Various embodiments may also be implemented primarily in hardware using,for example, components such as application specific integrated circuits(“ASICs”), or field programmable gate arrays (“FPGAs”).

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles described herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, it is to be understood that the description anddrawings presented herein represent a presently preferred embodiment ofthe invention and are therefore representative of the subject matter,which is broadly contemplated by the present invention. It is furtherunderstood that the scope of the present invention fully encompassesother embodiments that may become obvious to those skilled in the art.

What is claimed is:
 1. A network device for packet management in acommunication network having a plurality of subscriber stations andsupporting a plurality of communication services that have differentbandwidth and latency requirements, the network device comprising: amemory for storing computer-executable instructions; and a processor incommunication with the memory and configured to execute thecomputer-executable instructions to perform the steps of: determiningthat one or more of the communication services is a video service havingpackets carrying video frames; determining, for each of the one or moredetermined video services, a plurality of video frame discard levelseach of which has an associated frame discard criteria, an associatedestimated bandwidth demand reduction that would result from discardingthe video frames that meet the frame discard criteria, and an associatedestimated video quality reduction that would result from discarding thevideo frames that meet the frame discard criteria; and schedulingtransmissions to one or more of the plurality of subscriber stations bydetermining whether a required physical transmission resource value forsupporting all of a plurality of currently operating communicationservices in their current operating states is greater than a totalphysical transmission resources value, selecting, in the case that therequired physical transmission resource value for supporting allcurrently operating communication services in their current operatingstates is greater than the total physical transmission resources value,one of the plurality of video frame discard levels for each of the oneor more determined video services, wherein the selection is conductedsuch that an estimated quality degradation level for each of the one ormore determined video services resulting from a discard of video framesthat meet the discard criteria associated with the selected video framediscard level does not exceed a maximum quality degradation threshold,selecting, for each determined video service, all packets carrying videoframes that meet the discard criteria associated with the selected videoframe discard level for the determined video service and discarding theselected packets prior to a time for their transmission to one or moreof the plurality of subscriber stations.
 2. The network device of claim1, wherein the selected video frame discard level for each of the one ormore determined video services minimizes an estimated overall qualitydegradation level associated with the one or more determined videoservices.
 3. The network device of claim 1, wherein the execution of thecomputer-executable instructions by the processor further performs thestep of marking at least one of the packets with an identification ofthe associated video frame discard level.
 4. The network device of claim1, wherein the execution of the computer-executable instructions by theprocessor further performs the step of determining the required physicaltransmission resource value for supporting all currently operatingcommunication services in their current operating states.
 5. The networkdevice of claim 1, wherein the execution of the computer-executableinstructions by the processor further performs the steps of receiving arequest for admission of a new communication service, determiningwhether the sum of the required physical transmission resource value forsupporting all currently operating communication services in theircurrent operating states and an estimated physical transmission resourcevalue associated with the new communication service is less than thetotal physical transmission resources value, determining, in the casethat the sum of the required physical transmission resource value forsupporting all currently operating communication services in theircurrent operating states and the estimated physical transmissionresource value associated with the new communication service is not lessthan the total physical transmission resources value, whether the newcommunication service can be admitted in a degraded state, andadmitting, in the case that the new communication service can beadmitted in a degraded state, the new communication service in thedegraded state.
 6. The network device of claim 5, wherein the executionof the computer-executable instructions by the processor furtherperforms the steps of determining, in the case that the newcommunication service cannot be admitted in a degraded state, whetherone or more of the currently operating communication services can besufficiently transitioned to a degraded operating state to provideadditional physical transmission resources for admission of the newcommunication service, and transitioning, in the case that one or moreof the currently operating communication services can be sufficientlytransitioned to a degraded operating state to provide additionalphysical transmission resources for admission of the new communicationservice, the one or more currently operating communication services to adegraded operating state, and admitting the new communication service.7. A method for packet management in a communication network having aplurality of subscriber stations and supporting a plurality ofcommunication services that have different bandwidth and latencyrequirements, the method comprising: determining that one or more of thecommunication services is a video service having packets carrying videoframes; determining, for each of the one or more determined videoservices, a plurality of video frame discard levels each of which has anassociated frame discard criteria, an associated estimated bandwidthdemand reduction that would result from discarding the video frames thatmeet the frame discard criteria, and an associated estimated videoquality reduction that would result from discarding the video framesthat meet the frame discard criteria; determining whether a requiredphysical transmission resource value for supporting all of a pluralityof currently operating communication services in their current operatingstates is greater than a total physical transmission resources value;selecting, in the case that the required physical transmission resourcevalue for supporting all currently operating communication services intheir current operating states is greater than the total physicaltransmission resources value, one of the plurality of video framediscard levels for each of the one or more determined video services,wherein the selection is conducted such that an estimated qualitydegradation level for each of the one or more determined video servicesresulting from a discard of video frames that meet the discard criteriaassociated with the selected video frame discard level does not exceed amaximum quality degradation threshold; selecting, for each determinedvideo service, all packets carrying video frames that meet the discardcriteria associated with the selected video frame discard level for thedetermined video service; and discarding the selected packets prior to atime for their transmission to one or more of the plurality ofsubscriber stations.
 8. The method of claim 7, wherein the selectedvideo frame discard level for each of the one or more determined videoservices minimizes an estimated overall quality degradation levelassociated with the one or more determined video services.
 9. The methodof claim 7, further comprising marking at least one of the packets withan identification of the associated video frame discard level.
 10. Themethod of claim 7, further comprising determining the required physicaltransmission resource value for supporting all currently operatingcommunication services in their current operating states.
 11. The methodof claim 7, further comprising: receiving a request for admission of anew communication service; determining whether the sum of the requiredphysical transmission resource value for supporting all currentlyoperating communication services in their current operating states andan estimated physical transmission resource value associated with thenew communication service is less than the total physical transmissionresources value; determining, in the case that the sum of the requiredphysical transmission resource value for supporting all currentlyoperating communication services in their current operating states andthe estimated physical transmission resource value associated with thenew communication service is not less than the total physicaltransmission resources value, whether the new communication service canbe admitted in a degraded state; and admitting, in the case that the newcommunication service can be admitted in a degraded state, the newcommunication service in the degraded state.
 12. The method of claim 11,further comprising: determining, in the case that the new communicationservice cannot be admitted in a degraded state, whether one or more ofthe currently operating communication services can be sufficientlytransitioned to a degraded operating state to provide additionalphysical transmission resources for admission of the new communicationservice; and transitioning, in the case that one or more of thecurrently operating communication services can be sufficientlytransitioned to a degraded operating state to provide additionalphysical transmission resources for admission of the new communicationservice, the one or more currently operating communication services to adegraded operating state and admitting the new communication service.